Silas Bird, a twelve-year-old boy, lives with his father, a pioneer photographer, in the Mid-West of the USA. His mother died when he was born. His father is kidnapped by a gang of counterfeiters who believe that his photographic skills will help them. He tells Silas he will be back soon, and that he should stay and wait for him at home.

Then a horse belonging to the kidnappers returns to Silas, who takes this as a sign that he should follow his father and try to rescue him. He calls the horse Pony, and, though he had not ridden a horse before, sets off to follow the kidnappers through the woods, accompanied by his invisible friend Mittenwool, a ghost that only he can see.

The story is set in the 1860s, and in that sense is a historical novel, in that the historical background shapes the story. It is also a horse story, as Silas gets to know the horse that came to him, and took him on the quest to find his father. It is a ghost story, in which Silas's ghostly companion Mittenwool is not the only ghost. It is a crime novel, involving the hunting of a gang of counterfeiters. It is also a Bildungsroman, in which Silas grows up a lot, finding himself having to make critical decisions without adult guidance.

It's the kind of book I would love to have read when I was 12 years old.