James Gillespie is 12 years old. The world he knew is changing. Haunted by a secret, he has become a stranger in his own family. He is drawn to the canal where he creates a world of his own. He finds an awkward tenderness with Margaret Anne, a vulnerable 14 year old expressing a need for love in all the wrong ways, and befriends Kenny, who possesses an unusual innocence in spite of the harsh surroundings.

Critics find Ratcatcher to be hauntingly beautiful, though its story is somewhat hard to stomach.