During the plague summer of 1665, the court and most wealthy Londoners flee the capital. Thomas Chaloner is sent to Chelsea to investigate thefts from a private asylum supported by the Earl of Clarendon, but a series of stranglings soon becomes the more urgent danger.
The village is crowded with displaced courtiers, asylum inmates and Dutch prisoners of war housed in a theological college. Conflicting testimony links the institutions in unexpected ways, and Chaloner must find a killer able to hide among strangers before panic over escape, disease and murder overwhelms Chelsea.