Some want to coexist with humans, using genetic engineering in a macabre experiment to find a new source of blood. But some would rather go out in a blaze of glory - and UNIT's attempts to contain them could provoke another devastating war.

The Doctor strikes a dangerous bargain, but even he might not be able to keep the city from getting caught in the crossfire. While he finds himself caught in a web of old feuds and high-tech schemes, his new companion Sam finds out just how deadly travelling with the Doctor can be.

This novel is another in the series of adventures featuring the Eighth Doctor.