Ashley and Mary-Kate get a call all the way from Montana. A boy named Jason White Eagle says he needs their help because someone keeps robbing the ranch where he lives. First a beaded necklace, then a feathered Indian headdress, and now a big drum.
They figure out that each object is being stolen on the night of a full moon. This means that the Trenchcoat Twins have to work fast - because the next full moon is only a night away.