The fourth in the Stable Mystery Series. Doc Vet takes the three 11-year-olds to a horse breed exhibition. Someone is stealing brochures from four of the stalls where the horses are being shown. They attend a magic show-and some of the brochures are handed out. Why were they stolen? The trio investigate and find out the real reason for the magic show and the thefts-and they learn all about Sable Island in Canada and its herds of feral horses.