Dog Soldier

S1, E5: After a Cheyenne foster child goes missing, Walt and the team investigate the boy's birth family on the "Res." The stakes are raised when two more Cheyenne foster boys disappear and an unregistered sex offender is reported missing. The children in the group home insist that the boys were taken by a "dog soldier," a legendary Cheyenne warrior who can change shape from man to dog. Walt knows that the kidnapper was not a spirit, but a man who must be found before the unthinkable happens.