When a rabid cat is smuggled in to Britain, the spread of the disease goes unnoticed. That is until the first human falls victim to the terrible Mad Death.

Hillard moves to contain the outbreak inside the quarantine zone, while Anne searches for the source of the virus. Then another case is reported - outside the quarantine.

Efforts to contain the disease are threatened by sabotage. Both Hilliard and Anne find themselves in terrifying danger.