A well-to-do gambler is suspicious of the antics of a rather dull racehorse. The man goes into the colt's stable to investigate. A stablehand, Gates, and an exerciser, Ryan, find him there and Gates hits the gambler on the head, killing him. The dead man's daughter, Valerie, goes to Charlie Townsend and hires the Angels to find the murderer. Sabrina and the gambler's daughter, Valerie, go through her Father's things and find a card file on his horses Also, on an envelope they find a set of initials which, translated, mean white spot, lower left cheek written in the man's own hand. Sabrina gets a job as another exerciser, from Thad at the track. When she rides out on one of. the their horses, she meets an owner, Carter. As they watch Sabrina, both are attracted. Kelly tells him that she is writing an article. Ryan is friendly with Sabrina so that when she asks if a stallion with a white spot on his cheek killed Valerie's father, Ryan becomes suspicious. Bosley and Kris, posing as Arizona horse people, watch the workout. But when they offer to buy the horse, Keepback, Thad insists he's not for sale. Later he finds Bosley and Sabrina checking out the colt's lip tattoo. Gates is about to kill Sabrina when he drops dead of a heart attack. Bosley and Kris drive out of town to another stable where they find the real Keepback. The colt has been switched with its twin, a real winner from Mexico. Ultimately, the Angels find out that Carter was behind the whole scheme.