Summary:

The Clans are prospering. Life is good, and prey is abundant in the forests, plains, and even the coldest mountains. No natural disasters for a long time, and no Twoleg invasions.

Till now.

The Twolegs have created a new species of disease, meant to be used to treat what they call HIV, but the experiment for this cure has turned horribly wrong. This new species of virus multiplies like aphids on a leaf. They are lethal to all animals, but particularly so to cats.

House cats are dying. Alleycats are dying.

So are Clan cats.

There's only one way to save these feral warriors from certain death. A gene that offers immunity against this virus.

However, this gene can only work if the four different bloodlines – one from each of the Clans – are mixed together. And you know how it is with the Clans: no half-Clan heritage, please. So when the plague sweeps the forest, the Clans are plunged into panic.

Only one cat can help them all: the question is who, and how?