A boy is sent to live with his elderly aunt and uncle, and discovers a magical hiding place, which appears to him only when the clock strikes 13. He finds the people he meets there cannot see him - except for one girl, whom he forms a close friendship with. Children's drama, based on Philippa Pearce's novel, starring Anthony Way, Florence Hoath, Nigel Le Vaillant, Greta Scacchi, Liz Smith and Joan Plowright.

When Tom's brother Peter gets measles, he is sent to stay with his Uncle Alan and Aunt Gwen in a flat with no garden and an elderly landlady, Mrs Bartholomew, living upstairs. Because he may be infectious, he is not allowed to play outside and feels lonely. Without exercise he is less sleepy at night and when he hears the communal grandfather clock strangely strike 13, he investigates and finds the small back yard is now a large sunlit garden.