A young orphan girl, Portia, goes to live with her well-to-do aunt and uncle. As she is groomed to become a lady, she is confused by the young man who seems to be courting her. Surrounded by pretentious people who have no clue how to deal with teenagers, she soon loses her naïveté and thinks of running away.

Grimes, an amoral chimney sweep, occasionally likes to steal valuables from his clients. One day, on the verge of being caught, he frames his young apprentice, Tom, for the crime. Tom runs away and jumps into a river where, instead of drowning, he finds himself transformed into a mystical aquatic creature. Swimming and breathing effortlessly, he discovers a colorful underwater world replete with creatures both cruel and kind.

After the death of her daughter, wealthy housewife Julia Lofting abruptly leaves her husband and moves into an old Victorian home in London to re-start her life. All seems well until she is haunted by the sadness of losing her own child and the ghosts of other children.