from the back cover:
Horseracing is the sport of kings, perhaps because racehorses are very expensive animals. But when they win races, they can make a lot of money too - money for the owners, for the trainers, and for the people who put bets on them to win.

Silver Blaze is a young horse, but already the winner of many races. One night he disappears from his stables, and someone kills his trainer. The police want the killer, and the owner wants his horse, but they can't find them. So what do they do?

They write to 221B Baker Street, London, of course - to ask for the help of the great detective, Sherlock Holmes.