- “Engines don't swim, Henry - you were meant to deliver fish, not swim with them. You should know that by now.”
- ―Sir Topham Hatt scolding Henry for going onto the Coastal Run
Thomas is at the quayside and is about to take vans full of fish to Brendam Docks for Henry's train, The Flying Kipper. The fishermen, however, are using old equipment and Thomas begins to worry about being late. Then, a loose crate of fish drops onto his boiler, spilling fish all over him. His driver and fireman find it very funny, but Thomas is less than impressed and sniffs at the odour.
Later, he travels along the Coastal Run, but he is further delayed by a man waving a red flag. Thomas stops and the man informs him and his crew about some tracks that have been eroded from high tides and he has marked the spot. The driver decides to go inspect and they set off. They soon arrive at the unsafe area. The tracks are safe enough for a smaller engine like Thomas, but they cannot bear the weight of a heavy engine like Henry. The guard places a red lamp pole by the damaged track as a warning spot to engines and states that he will tell the signalman at the docks to close the line.
It is already dark once Thomas arrives at Brendam Docks, with Henry waiting for him. He is cross with Thomas being late and smelly. Thomas warns Henry of the danger, but Henry does not listen to Thomas' warnings and orders him to have his trucks hitched to the train. Finally, the Flying Kipper is away.
Inside the yardmaster's office, the yardmaster tells Thomas' crew that Henry is taking the Coastal Run; this shocks the driver, as he already told the yardmaster of the danger to big engines. The yardmaster quickly phones the signalman to reroute Henry, but Henry passes the signal box before the signalman can receive the warning, anxious to make up for lost time. Once Henry reaches the Coastal Track, he loses his luck for a fast run as heavy fog rolls in and neither he nor his driver can see the track ahead. By now, the damaged track has been completely submerged and Henry derails and plunges into the sea with his train, coming to a stop offshore and spits out a mouthful of seawater.
By the next day, when the tide is high enough for Henry and his fish to be craned from the water, he ends up in a barge full of fish with a seagull perched on his funnel, where the Fat Controller tells him that engines are supposed to deliver fish, not swim with them, which he should know. Henry is brought back to the docks by the barge to be lifted back onto dry tracks. Cranky expects Henry will have some "fishy" tales to tell, while some children laugh at Henry and call him a green whale, then a monster. Henry is most upset.
Finally, Henry is back on the rails and Thomas feels sorry for him. He comes to take him away for a washdown. After being cleaned, Henry apologises to Thomas for being rude to him. Thomas accepts Henry's apology, then jokes with Henry about smelling something--fresh air.
- Sir Topham Hatt
- Stephen Hatt (Not named; cameo)
- The Little Boys
- The Lighthouse Keeper (not named)
- James (cameo)
- Big Mickey (faceless; cameo)
- Bulstrode (faceless; cameo)
- The magazine story, A Fishy Smell may have served partial inspiration for this episode.
- This episode marks the last appearance of the Flying Kipper until the sixteenth series episode Whiff's Wish, excluding two stock footage appearances in the seventh series.
- An extract from this episode was put on the Planet Gullane website though was played at a faster speed.
- Big Mickey, Izzy Gomez, two schooners, the LT building and the steel company from TUGS appear in the episode. One of the schooners is seen with the wheelhouse of the shrimper named Jacqueline.
- Bulstrode can be seen on the beach, albeit without his face mask.
- Stephen Hatt makes a cameo as the boy who jokingly calls Henry a monster.
- Actual sardines were used for the fish that appears in the episode. This can be seen more clearly in a rare picture.
- This episode marks the first time an engine is seen with something in their mouth. In this case, Henry spat out water.
- This is one of the two episodes to feature Thomas' unused and alternative chuckling face from the third series, the other being the fifth series episode, Snow.
- In the US version, Alec Baldwin accidentally uses the term "guard" when the man leaves a red oil lamp by the damaged track.
- In the UK version when Thomas says "I can't help it, it's the fish!" the steam appears forward, then is played backwards, then played forwards again, meaning that the film was cut, but edited.
- After Henry reaches the fog, he loses two vans.
- In the US version, when Henry says "I can't see!" the first horn sound is barely audible.
- When Henry reaches the track marked for danger, the track closest to the rocks cuts off.
- Before Henry falls into the sea, his brakes are applied and his wheels stop moving, but when he runs into the sea, his wheels are moving again, despite the braking sound effects still being audible.
- In an overhead shot of Henry being towed in the barge, a seagull is seen nestled in his funnel. When Thomas buffers up to Henry to take him to get washed, the seagull is still there.
- When Thomas puffs away with Henry at the end of the episode, the puffing noise starts long before Thomas moves.
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