It tells the story of a poor orphan called Tom who is employed by the villainous Grimes, as a chimney sweep. One day he is accused of stealing from a rich household and runs away. As he is running he falls into a beautiful little stream and falls asleep, and becomes a Water Baby. In this new life, he meets all sorts of aquatic creatures, including an engaging old lobster, other water babies, and at last reaches St Branden's Isle where he encounters the fierce Mrs Bedonbyasyoudid and the motherly Mrs Doasyouwouldbedoneby.