Out in the fog-shrouded night of Victorian London, an evil force was lurking, waiting to strike. A senseless murder, over a strange artifact, was only the very beginning of the terror of The Iytean Menace. What was the ancient evil, and how had it been awakened? Where would it strike next?

The Time Lord and his Companions had been sent to the capital of Queen Victoria's realm to learn the source of a strange weapon that should never have been on Earth at all. What they found was a web of mystery and deception that led them, step by step, to a confrontation with The Iytean Menace.