|This article is about the episode. You may be looking for the Buzz Book or the magazine story.|
Every Summer, the Island of Sodor is busy with holiday makers visiting the Island to see the sights. With no sign of inclement weather, visitors often enjoy going to the mountains or the valleys, while children enjoy the seaside. One day, Thomas is busy on a coastal run taking children to the beach. When Thomas reaches the next station where Percy is taking some trucks to the harbour, Percy tells Thomas he wishes that he take children rather than trucks, but Thomas states that the children he was taking are the Vicar's Sunday School. He will also be busy in the evening but then offers Percy to take the children back home, in which Percy agrees to do so.
At Dryaw, Harold warns Percy there is inclement weather and to run very carefully. At the next station Edward warns Percy to be careful of an upcoming storm, but Percy knew what was going on. After the children enjoy a fun day at the beach, the weather turns bad and begins raining hard. Percy arrives at the station he came to earlier where Annie and Clarabel are glad when Percy arrives just in time to take the children home. Percy is disgusted by the rain, but despite thinking of being at the sheds, manages to get on with it.
As Percy begins his return journey, he battles onward through costal villages and the countryside. The heavy rain makes the river rise very quickly, Visibility is poor for Percy and battles the elements, but there is trouble ahead; a flood has flowed over the tracks, and the water extinguishes Percy's fire. His crew then try to find more firewood and his fireman suggests the guard gives some floorboards from the brake van. The guard grumbles that he had just swept the floor but still manages to help. Percy's firebox burns well and feels more comfortable again. Then Percy sees Harold, who thinks Harold has come to laugh at him, a parachute thuds on top of Percy's boiler. His driver laughs and tells Percy that Harold has thoughtfully given the crew hot drinks. Percy thanks Harold for the hot drinks, and Harold thanks them back before flying away.
Percy bravely continues on with his journey and loses steam, but keeps going. Percy makes several efforts, and triumphantly brings the children home. Thomas congratulates Percy for keeping his promise despite everything. The Fat Controller and Harold arrive and thanks both Percy, his crew, and the men. The Fat Controller is impressed with Percy's efforts, and congratulates Percy for being a really useful engine.
- Sir Topham Hatt
- Annie and Clarabel (do not speak)
- The Vicar of Wellsworth (does not speak)
- James (cameo)
- Stephen Hatt (cameo)
- Jeremiah Jobling (cameo)
- Mrs. Kyndley (cameo)
- Tidmouth Hault
- The Watermill
- The Lighthouse
- Hawin Croka
- The Country Line
- Cliff Side Track
- Arlesdale Lake and Mountain Line
- Arlesdale Castle
- Knapford Harbour (mentioned)
- This episode is based on the story of the same name from The Railway Series book, Percy the Small Engine.
- The episode can be seen in a Japanese game, Magical Adventure.
- In the restored version, the fade and the shot of Percy arriving at Elsbridge with Annie, Clarabel and the brake van are replaced by a cut and an extended shot of Thomas waiting for Percy.
- In a rare picture, Edward is wearing his exhausted face mask instead of his concerned face mask when he talks to Percy at Elsbridge.
- There are noticeable differences in the set between the original and the restored episode when the narrator says: "Children love the seaside."
- Deleted scenes from the first season of Thomas on Toby's Old Tramway are used at the beginning of the episode.
- The Coast Guard and The Shrimpers from TUGS appear.
- Some of the music in the US version and the early UK narration is absent.
- This episode was never released on Finnish DVD or shown on television. It was only released on a website in 2015.
- When Percy plunges onto the flooded tracks, water appears to come above his firebox. However, in the next shot, the water is below his buffers.
- When Thomas is on Toby's Old Line, Clarabel is facing the wrong way. Then in the next shot, Annie is facing the wrong way.
- Despite the fact that the water only reached Percy's footplate, he has a water line across his boiler when he meets Thomas at the end of the episode.
- In the shot of Percy's driver and fireman, the fence behind them is submerged, however in the close-up of the fireman, the fence is completely above the water. This changes again in the shot of the driver, fireman and guard carrying the wooden planks through the water.
- When Thomas talks to Percy at Tidmouth Hault, a red mark can be seen next to his left eye.
- Buzz Books - Percy's Promise
- Magazine stories - Percy's Promise, Going for a Swim! and Percy Gets Wet!
- My First Thomas Books - Percy and Harold
- My Thomas Story Library - Percy (discontinued)
- Books - Percy's Promise (book)
- Board Books - Percy gets Stuck
- Engine Adventures - Percy
In Other Languages
|Dutch||Percy's Belofte||Percy's Promise|
|German||Percys Versprechen||Percy's Promise|
|Spanish||La Promesa de Percy||Percy's Promise|
|Brazilian Portuguese||A Promessa de Percy||The Promise of Percy|
|Danish||Percys Løfte||Percy's Promise|
|Norwegian||Percys Løfte||Percy's Promise|
|Swedish||Percys Löfte||Percy's Promise|
|Finnish||Pekan Lupaus||Percy's Promise|
|Welsh||Addewid Pyrsi||Percy's Promise|
|Turkish||Percy'nin Sözü||Percy's Promise|
|Czech||Perchyo Slib||Percy's Promise|
|Polish||Obietnica Piotrka||Percy's Promise|
|Hungarian||Percy Fgérete||Percy's Promise|
|Slovak||Perciho Sľub||Percy's Promise|
|Slovenian||Poldijeva Obljuba||Percy's Promise|
|Romanian||Promisiunea lui Percy||Percy's Promise|
|Japanese||パーシーとこうずい||Percy and the Flood|
|Russian||Обещание Перси||Percy's Promise|
|Ukrainian||Обіцянка Персі||Percy's Promise|
|Thai||สัญญาจากเพอร์ซี||Contract from Percy|
Home Media Releases
|1. A Scarf for Percy 2. Percy's Promise 3. Time for Trouble 4. Gordon and the Famous Visitor 5. Donald's Duck|
|6. Thomas Gets Bumped 7. Thomas, Percy and the Dragon 8. Diesel Does it Again 9. Henry's Forest 10. The Trouble with Mud|
|11. No Joke for James 12. Thomas, Percy and the Post Train 13. Trust Thomas 14. Mavis (episode) 15. Toby's Tightrope|
|16. Edward, Trevor and the Really Useful Party 17. Buzz, Buzz 18. All at Sea 19. One Good Turn 20. Tender Engines|
|21. Escape 22. Oliver Owns Up 23. Bulgy (episode) 24. Heroes 25. Percy, James and the Fruitful Day 26. Thomas and Percy's Christmas Adventure|
| Canceled: Gordon Goes Foreign