As Christmas 1354 approaches, severe blizzards isolate Cambridge and leave its poorest inhabitants in desperate need of medical help. Among the travellers trapped in the town are Matthew Bartholomew's former fiancée Philippa and her wealthy husband, Walter.
A corpse found in a church is identified as Walter's servant, turning an uncomfortable reunion into a murder enquiry. Further violence closes around the visitors and Michaelhouse, forcing Bartholomew to confront old feelings while he and Brother Michael determine why someone is eliminating members of Walter's household.