Lemuel Gulliver (Jack Black) is happy to coast through life working in the mail room of a New York literary powerhose, until new employee Dan (T. J. Miller) is promoted to be his boss in less than a day, prompting Gulliver to blag an assignment to be a new travel writer, hoping to impress the love of his life, travel editor Darcy Silverman (Amanda Peet). Sent to explore strange happenings around the Bermuda Triangle, Gulliver's boat - the Knot for Sail - is hit by a huge storm and swept up into a giant inverted whirlpool, before he is knocked unconscious.
When he awakens he finds himself on the island of Lilliput... tied to the ground and surrounded by angry little men a 10th of his size!He has been 'captured' by General Edward (Chris O'Dowd) and paraded through the streets of Lilliput to be brought before the royal family - King Theodore (Billy Connolly), Queen Isabelle (Catherine Tate) and Princess Mary (Emily Blunt). Gulliver, nicknamed 'The Beast' by the Lilliputlians, is kept in chains in the island dungeon by the sea, where he meets and relates to another prisoner, Horatio (Jason Segel) - jailed for "unlawful courting" of Princess Mary, and previously the tallest man on the island by a few millimetres. Soon Gulliver is put to work ploughing the fields, but the warning bells sound to signal a Blefuscian attack - in which they try to kidnap the Princess, and burn the palace. Brave, and selfish, General Edward is off to save the day - but Horatio knows he cannot reach the Princess in time and begs Gulliver to help.
Horatio breaks his large friend free from his chains, and together they are off - first Gulliver drops the enemy spies into the village pond, before he does the only thing he can think to put out the flames in the palace and save the King -- to take quite a big leak. It works, the flames are doused, but he doesn't endear himself to Edward who gets a good bath in the yellow stuff. The Lilliputlians throw a huge feast for their protector, and start work on Gulliver's dream house by the sea. Life is pretty sweet for Gulliver - and the islanders are amazed at the 'stories' about his life (all scenes from famous movies). Horatio makes a successful move on the Princess with Gulliver's (and The Artist formally known as Prince's) help. When General Edward finally finds Gulliver's ship, Gulliver asks to stay. This is the final straw for Edward, who is asked to take a break by the King, allowing Gulliver to be promoted to the new General.
Hoping to regain his position, Edward sabotages the island defences. The Blefuscian launch a huge cannonball attack, and then their Armada approaches. Gulliver is summoned. He wades out into the sea, hoping to strike a truce with the enemy.
The Blefuscians instead attack, yet Gulliver's gut absorbs all the cannonfire, and then like an elastic band fires the metal back at the ships. Gulliver picks up the guideropes and hauls the Armada away, further strengthening his bond with the little people of Lilliput. (Former) General Edward skulks off to the enemy with plans from Gulliver's salvaged booty - a page on how to "Build your own robot". Edward returns to Lilliput to challenge Gulliver to a duel - inside a 6ft tall robot. He gives Gulliver a giant wedgie as he tries to run away, and shows Gulliver's true colors.
Gulliver is banished to the 'island they don't talk about', tied to a huge raft, while the Blefuscians take control of Lilliput and the King and Queen are locked in the dungeon. Meanwhile, Darcy has had to take the writing assignment - and is caught up in the same storm and shipwrecked on the island of Lilliput. She is captured by General Edward. Horatio escapes to find Gulliver and travel to the forbidden island.
Gulliver awakes on the 'island they don't talk about' - to find himself outside a giant house. He is snatched up by a little (but very tall!) girl, and forced to accept a new life as a doll inside a giant doll's house. That night Horatio finds Gulliver and encourages his friend to break free. Using the parachute from a dead pilot, they jump from the house and float away back to Lilliput. Gulliver finds Darcy chained up in the dungeons. He comes clean about his background - and his feelings for Darcy. Full of courage now, he breaks everyone free -- and goes to challenge General Edward in a winner-takes-all rematch.
Edward, in the giant robot, is ready - with a new secret weapon -- electricity! (They didn't seem to have electricity until Gulliver came along) Gulliver is losing badly. Horatio bravely grabs a horse, breaks his way into the robot, and turns off the power to the mighty weapon. It's a fairer fight. Gulliver beats the robot on the head a few times, and then gives him a robot wedgie, sending him back to sleep mode. The Lilliput King and Blefuscian Leader square up to fight again... so Gulliver asks -- "War - what is it good for?!".
They join in with his song, and everyone is at peace again. General Edward captures the Princess, but she beats him off. Back in New York, Gulliver is now a travel writer, enjoying more time with Darcy, with published articles about his travels framed on the wall. Dan, from the mail room, enters the office with a new mail room attendant, and is firmly put in his place.
As it ends, we see glimpses of Gulliver's articles, against the original Jonathan Swift novel content. JT, HowDoesTheMovieEnd. com.