Michelle does not know what to do when her new boxer Tombo's habit of chewing everything in sight puts a rift in her relationship with her best friend.
Thomas and his bionic dog McGrowl investigate when it becomes obvious that something is not quite right at Hiram Biddle's new obedience school for dogs.
McGrowl, a bionic superdog, is invited, along with his boy Thomas, to visit his original owner Edwina Tuttle, and finds himself on a wild goose chase, courtesy of the evil Milton Smudge.