There May be a Castle by Piers Torday
Mouse Mallory is 11 years old and he’s very little for his age. It’s Christmas eve and Mouse’s mum is hassling him to please help her out by packing his bag and getting ready for the short drive across the moors to visit Granny and Gramps. Finally, everyone is ready and in the car, Mouse still in his pyjamas sulking with his old stuffed toy horse, Nonky, and they’re off. Just as the blizzard starts.
A short time later several things, none of them good, happen all at once. Mouse is flung from the wreckage. He wakes up in the dark, the snow hiding all traces of humanity, totally alone except for a sheep and Nonky, but not a worn out old toy Nonky, a magnificent real-life (talking) horse! Mouse cannot remember how he got there or what happened, all he knows is that, according to Nonky, he has to find a castle. Now wearing a fine knight’s outfit, and with vague memories of a route he shouldn’t know about, Mouse, Nonky and the sheep march on through the snow.
There are lots of stories that talk about the mystery and power of imagination, but none capture its capabilities and limitations quite so well as this beautiful and moving story. Recommended for kids aged 10 and up.