Fifteen-year-old Mike (John Moulder-Brown) has just left school and starts a new job as a Public Baths attendant, under the wing of Susan (Jane Asher) - a streetwise twenty-something female attendant. Susan knows how to please the clients and advises Mike accordingly. A typical encounter is when he substitutes for Susan in tending to a female client (Diana Dors) who forces her attentions upon him. He quickly develops a crush on Susan that soon becomes an obsession as he stalks her around town. Jealous of anyone else who gives her attention, he is particularly incensed at her casual affair with his former sports teacher. In an attempt to promote himself, Mike hijacks a school cross-country run in the park. Observed by Susan, they engage in a playful tussle where she loses the diamond from her engagement ring in the snow. Gathering the snow, they return to the empty baths to find the diamond by melting the snow. In an unguarded moment, Mike attempts to seduce Susan but cannot follow through. His jealousy and exclusive desire reaches new proportions...