Des Kinvig (Tony Haygarth) runs an electrical repair shop in the small town of Bingleton. One day his store is visited by Miss Griffin (Prunella Gee), who is from the planetMercury and in need of Des' help. Kinvig's friend Jim Piper (Colin Jeavons) is a lifelong UFO watcher and is consumed by jealousy when he discovers that Kinvig has encountered extra-terrestrials. It is left intentionally ambiguous whether Kinvig's experiences with aliens are real or the product of an overactive imagination.
The show was produced by LWT, and only ran for one series of seven episodes. It was written by Nigel Kneale (more famous for Quatermass), directed and produced by Les Chatfield, with original music by Nigel Hess.