Format: Paperback

Publisher: Target Book 1979

Pages: 110

A mysterious cloud drifts menacingly through space...

A sudden energy flash and the Doctor is infected with the Nucleus of a malignant Virus that threatens to destroy his mind.

Meanwhile, on Titan, human slaves prepare the Hive from which the Virus will swarm out and infect the universe.

In search of a cure, Leela takes the Doctor to the Foundation where they make an incredible journey into the Doctor's brain in an attempt to destroy the Nucleus.