Percy discovers some wobbly rails, but no-one will listen to him. When Thomas is sent along the track, he runs into trouble and Percy comes to his rescue. Sir Topham Hatt promises to listen to Percy more in the future.
A tractor named Fergus goes to help Mavis, Bill, and Ben at the quarry but the twins hate his ordering them around. When he tells them a wall isn't strong enough to go near, they head for it, and Fergus risks his own life to save them.
Henry feels ill, but Thomas and Percy don't believe him and leave a long line of trucks for him to haul. The trucks become too much for poor Henry and he soon breaks down completely and Emily has to come to his rescue.
James brags so much about his good looks that when a filthy barge named The Queen of Sodor arrives, Gordon mentions the importance of bringing it in so James will think it's a royal person and volunteer to deliver "her".
Arthur, a hard-working obedient engine, is brought in to help Thomas and Percy. Thomas plays a trick on him by telling him to stop the freight-trucks' singing so the trucks set Arthur up to have an accident.
Toby always loves looking at the island's windmill, but one day he is so distracted he crashes with some flour into a sail and is determined to help his friend not to lose his business, especially when lightning ruins it more.
Donald and Douglas jump at the chance to visit Lord Callum's castle to set up for a reopening-party since they're homesick, but become nervous that a monster is in the loch they become stranded near after a landslide hits the break-van.
Arthur and Thomas are disappointed when Thomas is chosen to run the new harbor-line since Thomas hates fish but Arthur loves the harbor. A track set wrong that causes Thomas to separate from the freight-trucks and sink may help them both.
Diesel is needed to help Thomas and Fergus, and when he causes trouble Fergus tries to instruct him. Diesel lies that Fergus is ordered to work at the smelter's, but he is afraid enough of it to run away.
Gordon wants to take the Duke and Dutchess around Sodor, but their private engine Spencer does, and is determined to show off how good he is. He ignores Gordon's advice to stop for water and Gordon has to help him.
Rusty warns that the old bridge is unsafe since it's cracked, but Duncan ignores him, and leaves in a hurry. He chooses to cross the bridge to get more coal for himself, and it begins to give way with him stranded on it.