Along the Oregon Trail with the Tim O'Brien family and Army Remount Serviceman Dan Gallegher, chestnut stallion Shannon is stolen by professional horse thieves. Reluctantly, the family and mare Pegeen continue without him; Shannon is sold to a racing man, escapes to be picked up by a cavalry sergeant, then is stolen by Indians. Another escape and several mistreatments later, he is wandering through Oregon, by now a confirmed misanthrope, when Dan finds him and returns him to the O'Briens--just after Pegeen foals his colt. (Talk about planned parenthood!) Realistic and involving until the reunion which occasions horse happiness and human contentment: Dan will marry Maureen O'Brien and Tim shows he's adjusted to the move. No runaway but a safe bet.