An ancient Martian spaceship is unearthed in London, and proves to have powerful psychic effects on the people around.

After a mysterious explosion leaves a large fissure in the ground, two young boys are confronted by an unknown phenomenon that inflicts severe radiation burns on one of them. There follows a spate of attacks at radiation establishments as the inexplicable life-form plunders radium stores. Dr Royston, an expert in atomic research, is brought in to explain and curtail the activities of this alien creature before it causes disaster.