We see footage of the fishing village, Manchester-by-the-Sea, Massachusetts. Lee Chandler (Casey Affleck) is on a boat with his 8-year-old nephew, Patrick, teasing him, asking who he would rather hang out with him or his father (who is Lees brother, Joe). Patrick answers his father which amuses Joe, in the bridge of the boat. We aren't told but we find ourselves roughly eight years later, in Boston. Lee works as a handyman for an apartment building, dealing with all the tenants who are all rude or difficult in some way the first one is argumentative; the second one loudly talks on the phone how she wants to have sex with the handyman cleaning her shit from the toilet; the third is a woman who accuses him of wanting to see her naked when he suggests turning on the shower to see if it leaks.
That woman complains to the building manager. Lee points out that he is working four buildings and all the money goes to the manager. He is asked to apologize to the woman but he remains ambivalent because he did nothing wrong in the exchange. Lee goes to a bar and a woman spills some beer on him, seemingly intentionally, to start up a conversation. He is standoffish with her. Later, two businessmen across the bar note Lee and discuss him briefly. This prompts Lee to approach them, antagonistically. He punches them both.
He goes home and falls asleep watching sports on TV. It's now winter. Lee shovels snow. He gets a phone call which he keeps short simply asking the caller when something happened and saying hell come up immediately. Driving, Lee calls the building manager from his phone and says he has to go out of town for a week or two.
He gets irritated with the traffic as he makes his way up north. Lee arrives at a hospital. He asks a nurse if he is dead and is told he passed away an hour ago. He remains stoic in response.
George (CJ Wilson), a family friend, explains that they were on the boat that morning and he just fell over. The doctor comes and introduces himself to Lee. Lee asks where his brother is and is told he can see him downstairs if he wants. The doctor explains that his heart was very weak and it finally gave out. Lee asks them to call his uncle in Minnetonka, Minnesota and also to call his ex-wife, Randi.
We flashback to eight years earlier. Joe (Kyle Chandler) is in the hospital bed with his wife, Elsie (Gretchen Mol), his father, and Lee. They learn that Joe has congestive heart failure and will only live for another five to ten years. Elsie freaks out at this news. When the family keeps the mood light with humor, she storms out. In the present day, Lee is brought down to the morgue to look at the body. Joe is there, dead, cold, lifeless. Now we flashback to seven years earlier, like in the first scene of the film.
Lee is on the boat with an 8-year-old Patrick. He teases him about a shark that is going to eat him but Patrick is unfazed, a tough Massachusetts kid. He gets a bite on his fishing pole and begins to reel it in. We cut to the present.
Lee rushes up to Manchester to inform Patrick about his father. He drives through the town and has a flashback of seven years earlier, returning home to his wife, Randi (Michelle Williams) who is sick in bed. He says hello to his seven-year-old daughter, playfully teases his five-year-old daughter, and picks up his eight-month-old son. He then kisses Randi despite her being bedridden. He tells her about his day, fishing with Patrick. In present day, Lee stops by Patrick's school and is told his nephew is at hockey practice. He goes to a hockey rink in Gloucester and sees a 16-year-old Patrick on the ice, fighting with another kid. When Patrick sees Lee is there, from out of town, he knows immediately something bad has happened with his father.
While the coach chastises him for fighting, he tells him to "fuck his fucking ass" and is told he's benched. He responds with Ask me if I give a shit. The coach becomes furious until the other kids point out that Patrick's uncle is there and his dad is in the hospital. The coach begins to backpedal, becoming sympathetic towards Patrick. Patrick's friends comfort him. Patrick is in Lee's car, having been told the news. Lee has to return to the hospital to sign papers and asks Patrick if he wants to see his dad.
They stop in the parking lot and Patrick debates whether he wants to see his dads body. He finally decides, Lets just go so Lee drives off as Patrick tries to exit the car. Patrick gets angry, telling him he meant, "Let's just go INSIDE. "Immediately after seeing his father in the morgue, Patrick wants to leave. Lee and him get back to Joe's house and Lee cant open the garage door because he doesn't have the opener. Inside, Patrick asks if he can invite some friends over. Lee says its okay. Patrick is comforted by his girlfriend, Silvie (Kara Hayward), and his two guy friends.
That night, Patrick asks Lee if Silvie can spend the night because his dad always let her. Lee asks Patrick why he is asking him. Patrick tells Lee that her parents thinks she sleeps downstairs and if they ask, "can he tell them she isn't staying in his room?" Lee becomes very silent and then asks if he's supposed to tell Patrick to use a condom. Patrick tells him that his dad already had that conversation with him. Lee sits up in the guest bedroom, thinking. We flashback to six years earlier, when Patrick, Joe, and Lee returned home to find Elsie passed out on the couch after drinking all night with no pants or underwear on. Lee has to usher the 8-year-old Patrick upstairs. The next morning, in present day, Patrick is seen emailing his mother.
Downstairs, Lee makes arrangements with a funeral home. At school, the hockey coach excuses Patrick for his foul language but orders him to take time off from practice. After school, Lee drives Patrick to see the lawyer for the reading of Joe's will. Five years earlier, we see Lee and his friends playing Ping-Pong in the basement of the home he shares with his wife and kids. They're all loud and drunk and Randi comes down and yells at them to leave because its 2 AM in the morning and her children are upstairs. In the lawyers office, Lee learns the will dictates that he will be Patrick's guardian which is a responsibility he never discussed with his brother; because Joe probably knew he wouldn't have agreed to it. He is told the will stipulates that Lee will provided with expenses for Patrick's clothes and food and that the house and boat are owned outright. Lee explains that he cant commute from Boston every day until Patrick turns 18 but the lawyer points out its expected that Lee relocate to Manchester.
He has been left up to $5,000 to help with the move. Lee asks if Patrick can move in with his uncle in Minnetonka but Joe had told the lawyer that he didn't feel Patrick had the same bond with him that he does with Lee. We flashback again to five years earlier, in Manchester, after Lees friends have been kicked out of the house. He is walking home, on a snow-covered street, with a bag of groceries hes got from a nearby store.
He hears fire engines in the distance and we see an immediate panic on his face. In the lawyers office, the lawyer suggests Patrick stay with his mother but Lee shuts that idea down immediately. We flashback once again to five years earlier, where Lee comes home to find his house on fire. Randi has made it outside but she has become hysterical, screaming that her three children are still inside.
Lee stands, frozen, still holding the bag of groceries. In present day, Lee leaves the lawyers office, realizing he has no choice but to move back to Manchester. In flashback, we see Lee at the police station, explaining that he had been partying with friends and had been high and drunk. Randi kicked them out and he went downstairs to build a fire in the fireplace to warm up the house.
He goes on a 15 minute walk to get more beer and halfway there, wonders if he put the fireplace screen up. He figures it will be okay and continues to the store. He tells them a log must have rolled out because when he returned, the house was on fire. Randi was saved because she slept downstairs but the children were upstairs and when the furnace blew, the firefighters couldn't safely retrieve them. The detectives tell Lee that's all the questions they had. Lee asks why hes not going to be charged with a crime but they point out it was a million dollar mistake. He is escorted outside the interview room.
Filled with guilt, he grabs a policeman's gun from his holster and tries to shoot himself in the head. But cops take him down and retrieve the gun. Lee and Patrick leave the lawyers office and talk about Joe's boat. Lee plans on selling it but Patrick points out its his boat and hes planning on maintaining it, despite the expenses. Lee points out that Patrick doesn't even have a drivers license but Patrick tells him hes going to run the boat with George, their family friend who works at the wharf.
Lee tells Patrick he's going to "knock his fucking block off". A businessman (a cameo by the film's director Kenneth Lonergan) passes and comments, "Great parenting. " Lee gets angry with him and tells him to mind his own business. Patrick and Lee make it to the wharf. George tells them the boat needs a new motor which Lee points out they have not been given any allotment to purchase and asks George if he wants to purchase the boat.
Patrick argues that hes not selling it while George tells Lee the boat is going to bleed Lee dry if they just leave it docked. Lee tells George that they're moving to Boston anyway and George comments that Lee can come and stay with him on weekends. When Lee asks if George wants to be his guardian, both Patrick and George explain that he has five kids already. On the dock, Patrick yells at Lee for asking George to be his guardian. He notes that he doesn't want to be sent to Minnetonka to live with his uncle and asks about staying with his mother. Lee tells Patrick that that judge would not allow Patrick to stay with her (a hint at the aftermath of her excessive drinking that we've seen in flashbacks) and adds that no one knows where she is. Patrick tells her she's in Connecticut and he talks to her on occasion via email.
The two of them stop by the funeral parlor where the undertaker goes over the funeral with Lee. Outside, Patrick says he thinks the guys somber act was phony because every customer he meets with, every day, has gone through the same loss. He asks Lee why they cant bury his father but Lee tells them the ground is too hard because of the cold and they have to wait until spring. Patrick asks what happens to the body until then. Lee tells him they put him in a freezer until the ground thaws out.
Patrick tells him the idea of his dad in a freezer freaks him out. Lee tells him its not HIM in the freezer; just his body. Patrick suggests using mini-steam shovels to dig a hole in the ground. Lee tells him using heavy equipment in a cemetery would offend the families of those buried there. Patrick asks about burying him somewhere else and Lee tells him this is where Joe arranged for his plot and if Patrick wants to go through the long process of changing everything, he can.
Patrick tells him he just doesn't like his father being in a freezer. Driving home, Patrick asks if he can be dropped off at his girlfriends house. When they arrive, Patrick reveals that he's at the house of Sandy, not Silvie, the girlfriend that we've met before. Patrick asks Lee not to say anything.
Patrick has band practice with Sandy and their friends. Lee waits for him outside and is greeted by Sandys mom who asks him if he wants to join them for supper. Lee declines, picking up a romantic interest from the woman. He says hell come back when Patrick is ready. She tells him they say they usually do their homework together until about 9:30 PM but notes that they most likely are being sexual instead.
We see Patrick and Sandy kissing and undressing in her bedroom. Her mother knocks on the door, forcing them to break up the activity. Lee is back in Joe's house and gets a phone call from Randi, his ex-wife. She has heard about Joe's death and wants to give her condolences. She asks if it would be okay for her to attend the funeral and he says, Of course. She then confesses that shes pregnant and wants him to know now because it will be obvious when he sees her again. Lee tells her he has to pick up Patrick and she tells him that's okay; she just wanted to make sure it was okay for her and Josh to attend the funeral. We flashback to five years earlier.
In the same living room Lee is currently in, there is a memorial service for his children. Randi is being comforted. Lee is in the living room, numb. He takes off his shoes, making himself comfortable, not able to mourn. The next day, there is a service at Georges house for Joe. Silvie is there, comforting Patrick. George tries to talk to Lee but hes crestfallen and lost in his thoughts.
George begins to shout out to his wife to get Lee some food but she says she cant hear him; Lee tells him he doesn't want to eat and George tries to relay this message and it goes back and forth. Back at Joe's house, Patrick asks if Silvie can stay over but Lee tells him no because he doesn't like her. For the first time, Lee has treated Patrick like a guardian and not a buddy. Patrick seems somewhat impressed by this and he goes to talk to Lee, asking why he is staying in the guest room instead of Joe's bedroom. (Obviously Lee is still going through the motions as if Joe was still alive.
) Lee explains hes fine in the guest room because hes going to move back to Boston soon. Patrick argues that Lee lives as a janitor in Boston and there's no reason he couldn't relocate to Manchester, while Patrick would be leaving his high school and all his sports teams and his friends and his two girlfriends if he left. He asks Lee why he cares where he lives. We flashback to five years earlier Lee packs up his car, leaving town shortly after losing his children. Joe asks him where hes going to stay and he says a motel. Joe then encourages the 10-year-old Patrick to say goodbye to his Uncle Lee. (Its now obvious that Lee doesn't want to relocate to Manchester because it reminds him of the loss of his three children).
That night, Patrick opens the freezer, looking for a snack. Some packages of frozen meat slide out. He tries to put them back in and hits his head on the door. He then begins having a full on panic attack and Lee comes in to calm him down. Patrick is taken up to his bedroom, still panicked and angry. He tells Lee to leave him alone but Lee insists on staying, asking if Patrick's having a breakdown and that he should be taken to a mental hospital if he cant handle the sight of frozen chicken.
Patrick admits he doesn't like his dad being in the freezer and tha'ts what set off the panic attack. He tells Lee he is calmer now and asks him to get out but Lee refuses, now fully taking on the role of a guardian. Its five years earlier Lee moves into the apartment building he was seen fixing at the beginning of the film, which he shows off to Joe and a young Patrick. Back in present day, Lee is still in Patrick's bedroom. He tells him hes decided to wait until the school year ends to move them to Boston. Patrick asks if hes asking him or telling him. Lee says hes telling him whats best.
Patrick asks why he cares whether or not its okay with him because hes already decided for the both of them. Lee argues that Boston is only 30 minutes away but Patrick finds this comment hysterical, stating its a 90 minute drive in traffic. Lee drops Patrick off at school and gives him some money, asking why Patrick needs it because hes given money for helping George with the boat. Patrick tells him hes saving that money to buy a new motor. Back at home, Lee enters Joes bedroom and see photos of his family on the dresser. He abruptly smashes his fist through a window. As his knuckles bleed, the phone rings. It's Elise, Joe's ex-wife and Patrick's mother, on the line.
Lee doesn't know how to respond so he just hangs up. That night, Patrick asks Lee why he didn't tell him his mom called. She has emailed him that shes in Essex and wants Patrick to see her new house and meet her fiancÚ. He says he hung up because he didn't know what to say and he didn't tell Patrick because he didn't know what to say to him. Patrick suggests living in Essex with his mom and states shes not an alcoholic anymore. This way, he can stay at the same school and keep his friends and the boat and Lee can go back to Boston. Lee says he wont allow that but he will talk to her and if she sounds normal, hell let Patrick have lunch with her. While Patrick works on the boat he inherited, Lee goes around the boat yard looking for a job.
But he seemingly has a bad reputation in town and people are reluctant to employ him. On the way back home, Patrick tells Lee that the piston is about to give out in the motor. Lee tells him they cant afford a boat if they cant hire someone to work on it and no one will work on it if the motor is broken. Patrick asks Lee to drop him off at Sandy's house for band practice. When they arrive, he asks him to stay for dinner because Sandy's mom likes him and that will give Patrick time to get sexual with Sandy. Lee reluctantly agrees. That night, Sandy's mom tries to chat up Lee but he says very little. Upstairs, Patrick tries to put a condom on but trips over Sandy's doll house.
She complains that her grandmother gave it to her. Downstairs, Sandy's mom asks whats going on and Sandy complains about the doll house and Sandy's mom shouts that it belonged to her mother. Sandy's mom excuses herself upstairs and knocks on the door. Patrick and Sandy have to get dressed again to pretend like they're working at her computer. Sandy's mom tells her daughter that Lee wont talk to her and she cant sit down there any longer with him. Driving home, Patrick sardonically thanks Lee for his help. Patrick is driven to Elise's house in Essex. Its been years since shes seen her son and she marvels at how big he has gotten.
Patrick is introduced to her fiancÚ, Jeffrey (Matthew Broderick), and they all sit down for lunch. Patrick notes all the religious paraphernalia around the house (seemingly the product of Elise's AA program). Jeffrey says grace and then Elise chastises Patrick for not saying amen. He points out he did say it but quietly. Elise tells him shes sure her new life is a shock to him and they continue having awkward conversation, with her stating that he doesn't need to be formal and he should treat their house as his home, too.
Jeffrey asks Patrick what hes studying in school and he responds, The usual stuff. Elise excuses herself to the kitchen, leaving Jeffrey and Patrick alone. Jeffrey continues asking awkward questions, like if Patrick has gotten any string beans. After a while, he excuses himself into the kitchen, too, to check on Elise.
Back in the car, Patrick tells Lee that his mom was really nervous and her fiancÚ was really Christian. Lee comments that it sounds like Patrick's mother is doing better and not drinking or in the psych ward. Patrick gets angry, accusing Lee that hell do anything to get rid of him. At home, Patrick receives an email from Jeffrey, telling him his mother would prefer they not rush into future visits and that all discussion with her should now go through Jeffrey.
Downstairs, Lee asks Patrick if he wants to invite friends over but Patrick is dismissive to the idea. Lee enters Joe's den and sees all the handguns on the wall. Patrick is standing behind him, unbeknownst to him, and asks Lee which one of them he plans on shooting. Lee tells him the guns are worth a lot of money and they could sell them for the new motor. Cut to the boat with a new motor installed.
Patrick drives the boat alongside George as Lee watches. Later that day, Lee walks back to his car and runs into Randi and one of her friends. Randi is pushing her new baby in a stroller. Her friend excuses herself to get the car, leaving Randi and Lee time to talk. Randi goes into a heartfelt speech about how she would like to have lunch with him and how she feels awful for the terrible things she said to him (after their children died).
She admits she was acting out because she was heartbroken and still is; but she knows he is, as well. She continues to apologize but he gets uncomfortable and tells her no to the lunch. Randi tells him she sees him walking around now and wants to let him know she was wrong; he ends the conversation shortly and leaves. The exchange has rattled Lee.
He goes to a nearby bar and punches a guy who accidentally clips him as he walks by. George is there and he breaks up the fight. Lee is taken to Georges living room, banged up, while George and his wife discuss Lee and the fight. Life becomes peaceful. Patrick shows Sandy his boat. He lives in harmony with Lee. Sandy spends the night and they finally are able to be sexual (we see them entangled in the aftermath). Lee now has a job as a handyman in Manchester.
He helps a man with his hot-water heater. The man recognizes him as Stan Chandlers son and notes that he used to play chess with his dad. He also carelessly notes that he heard one of his sons has died. Lee makes dinner, heating up sauce for spaghetti.
He goes to rest on the living room sofa and opens his eyes to see his two daughters seated beside him. One asks, Cant you see were burning? He tries to assure her shes not burning but wakes up when a smoke alarm sounds he has fallen asleep and the sauce has burned on the stove, causing the house to fill with smoke. Over dinner, Lee tells Patrick that he got a job as a handyman in Boston but for only two buildings instead of four. Lee tells Patrick that he doesn't have to come to Boston because George is going to take him in two of his five kids are moving out soon anyway. They can rent out Joe's home until Patrick turns 18 and then he can move back in. When hes 21, he can sell it or stay in it and they can hire the boat out after the summer ends. Lee will remain the trustee but all the financial things set up for Lee will transfer to George. Patrick asks if George and his wife will be his guardians and Lee tells him they're going to adopt him.
This upset Patrick and he begins to cry. Spring has come and they are finally able to give Joe a burial service. Randi is there with her baby and her husband. Afterwards, Patrick is told Lee will stay with him until July; he doesn't even have a place to stay in Boston yet. Hes declined the apartment the building offers him to do handiwork and is in search of a bigger place in case Patrick ends up going to college in Boston and needs to stay overnight sometime. Patrick says hes not going to college so Lee tells him then the extra room will be for all his shit. Lee tells Patrick that he would stay there if he could but its impossible to recover from what happened (to his children). The film ends with Lee and Patrick on the boat, on the sea, just like the opening of the film.