Thomas is sent to fetch a Christmas tree, much to the annoyance of the mainline engines. After Thomas leaves to collect the Christmas tree, all the engines are very excited about the celebrations. But later, they realise that Thomas hasn't returned home. The Fat Controller tells the engines that Thomas must be found, so he sends Donald and Douglas to find him. With a van between their tenders and a snowplough on their fronts, the Scottish twins set off. They find the snow very deep at Wellsworth and, in the cutting before Gordon's Hill, they find Thomas stuck in the snow. James and Edward, clearing the snow from the opposite direction, come to help too. After the rescue, all the engines return home in time for the Christmas party. Father Christmas comes to the party aboard Harold, and gives Thomas and Percy balloons.
- Donald and Douglas
- Sir Topham Hatt
- Edward (does not speak)
- Percy (does not speak)
- Toby (does not speak)
- Duck (does not speak)
- The Works Diesel (does not speak)*
- Annie and Clarabel (do not speak)
- Harold (does not speak)
- Father Christmas (does not speak)
- Bill and Ben (cameo)*
- Daisy (cameo)*
- BoCo (cameo)*
- Henrietta (cameo)
- Bertie (cameo)
- Trevor (cameo)*
(*Absent in My First Thomas edition)
- Because this book is a television tie-in, Donald and Douglas appear in black. It is also notable that the only engines present at the Christmas celebrations are those who had been featured in the television series at that point – Bear, Oliver, and Mavis are absent. Strangely, the Works Diesel appears.
- In the original publication, Donald and Douglas are painted black, but in the My First Thomas edition, they are blue.