1361. Plague has returned to England – 13 years after the devastation of The Black Death. As destruction advances towards his estate in Kent, Oswald de Lacy leads his family to the safety of a remote castle in the marshes – where his friend Godfrey is preparing a fortress to survive the coming disaster. The rules are clear: once the de Lacys and other guests are inside the castle the portcullis will be lowered and no-one permitted to enter or leave until the Pestilence has passed. And then a murderer strikes. Oswald is confronted with a stark choice – leave and face the ravages of the plague, or stay and place his family at the mercy of a brutal killer.