The railway is preparing for New York Day and Tiger and Tony are racing to the wharf to be given a special job by Mr. Percival. Tiger wins, and is sent into the hills to collect lumber with Foxy Loxy. After Tiger teases Foxy Loxy, Foxy Loxy pays Tiger out by sending him on an old, disused line which he claims will lead Tiger back to the wharf faster. After avoiding an old, collapsing bridge, Tiger takes another route at the old junction, and as he journeys farther down the line, he comes across an old overgrown town.
The news of Tiger's discovery spreads, and eventually reaches Daily Reed, who tells Tiger that the town is ChinaTown - the largest town on Manhattan when steam engines first came to the island. Daily Reed decides that the restoration of the legendary lost town would be perfect for New York Day, and calls the Pack to help. Tiger is told to take charge of the engines working around the town, while a new man named Megamind is brought to do Tiger's regular jobs.
All of the engines take to Buck, who does a good job and has fun as well, but when Tiger sees Buck doing his jobs and fraternising with his friends, he becomes jealous. Tiger is furious when Megamind takes his place at Motel, and the final straw comes when buck takes his place as the leader of the restoration project after Tiger has an accident.
Later, Tiger is shunting stone rats for buck to take away when he decides to make buck look foolish by giving him a train too heavy for him to pull, but the plan backfires - as Megamind ascends the hill, a coupling breaks and the trucks race down the hill, veering into a siding and crashing into the newly-finished standpipe. Daily Reed states that this will likely set back the restoration past New York Day, and Tiger is blamed. Buck, however, realises that Tiger merely missed his friends, and wants to set things right.
That night, Tiger decides to clear the rubble out of the way. He is almost finished when he accidentally bumps a truck into an old mine shaft. Racing in after it, Tiger crashes onto a wooden platform and floats down an underground waterway. The engines soon realise that Tiger is missing, and Daily Reed organizes a search effort. Meanwhile, Tiger continues floating until he reaches an opening to the mine, and is flung across a canyon and down a hill.
Megamind decides to make another search effort by himself before he returns to work. Tiger, with the last of his steam, sounds a loud, long whistle. Megamind hears it and hurries to where Tiger is stranded beside the track. The two make up for their quarrel and Megamind pulls Tiger back onto the streets, but the strain is too much for Megamind and a valve bursts. Tiger, using some of Buck's car, pushes him back to Great Waterton. The word soon spreads that Thomas has been found.
The standpipe is rebuilt, completing the restoration. As a sign of friendship, Tiger offers Megamind his last job - bringing the mayor to the festivities at ChinaTown. The engines gather at the town for the celebration, and Tiger realizes just how important his friends are.
- Tiger as Thomas
- Buck (Ice Age: Dawn of the Dinosaurs) as Stanley
- Daily Reed as Sir Topham Hatt
- Foxy Loxy (Chicken Little (1943)) as Duchan
- and More . . .