Builders working on a London Underground extension unearth what they think is an unexploded bomb. When renowned scientist Bernard Quartermaster investigates, he discovers something far deadlier - an ancient spaceship containing the remains of insect-like aliens, whose psychic abilities still represent a deadly threat to the human race. Sci-fi horror based on the classic TV series, starring Andrew Keir, Barbara Shelley, James Donald and Julian Glover.

A mysterious artifact unearthed below a London Underground station proves to have powerful psychic effects on the people around.