Trama

Henry is annoyed to hear Percy carrying on about how well he performed a rescue despite a flood. Percy wants to go past the forbidden area at the harbor, despite Thomas' warning against it, and ends up sinking into the surf.

At the Harbour at Brendam, a tired Henry is looking to rest, but instead he finds Percy telling two Engines about the time he braved bad weather to help Thomas. Percy uses the phrase "Water's nothing to an engine with determination." While the engines shower him with praise. Henry arrives and angrily sends them away, claiming that the shed is only for engines belonging to the Fat Controller and calls the two silly. As the two engines leave, Percy as cross at Henry for sending them away as he was enjoying himself and says the two engines are not silly. Henry says they are and also thinks Percy is silly for his remark about water. Percy brags to Henry as he's not afraid of water, he likes it and runs off, singing about the time that Henry refused to leave a tunnel in case the rain ruined his paint, to his annoyance.

Percy finds Thomas looking at a "Danger" sign on the quay. Thomas tells Percy that they mustn't go past the it, recalling when he disobeyed one and fell down a mine. What Percy doesn't realize is that the foundations of the quay have sunk, causing the tracks to slope downward into the sea. As a result Percy, who's now feeling very cheeky, remarks that the sign is stupid and makes a plan to pass it.

One day, Percy is taking a line of trucks to the Harbour. He secretly asks them to give him a bump once they get to the quay. The trucks happily agree, having never been asked to bump an engine before. Percy thinks that he can stop the trucks whenever he likes, but every wise engine knows that trucks are never to be trusted.

At the quay, the trucks seize the opportunity and bump Percy hard enough to knock his crew off the footplate. Percy is frantic and urges the trucks to stop, but they ignore him and cause him to slide downward into the sea. From a nearby boat, the Fat Controller scolds Percy for his disobedience. Percy begs to get out, but the Fat Controller sternly refuses, explaining that they can't do that until high tide and hopes that this will teach Percy to obey orders. When night falls, floating cranes are brought in to pull Percy from the sea, who is now cold, filthy and unable to move.

The next morning, Percy's taken to the works to be cleaned and mended on Henry's goods train. Henry finds the incident very amusing, telling Percy he needs more determination and suggesting that he'll like the water better next time. Percy, however, hopes there won't be a next time.