The smallest of the shrew family, Little Caboose wishes he were the "engine" in his family's traveling order so that he could lead his brothers and sisters as they follow Mama through the shady forest. When he meets a new friend, he playfully chases him into a clearing. Suddenly, he finds himself lost and alone. As night settles around him and the dangers of the forest close in, Little Shrew Caboose learns that he must be brave if he is to find his way back home.