Mystery Rider (Horses and Friends)

Thirteen-year-old Kate Ferris has a problem. Melissa Tolbert, a wealthy girl who has been snotty to Kate and Tori at school, is one of the boarders at Kate's family's new boarding stable. When Melissa suddenly turns nice, Kate is suspicious. The last thing she needs is more trouble. Then a stunning black horse and mysterious rider trot up the road past Kate's house at dusk. Is it Melissa, playing a dangerous game? Or might the horse be stolen? Kate and friends Tori and Colt are determined to solve the mystery.