When firemen are called to an intense blaze at the Grange in Melverley, they find the bodies of Christie Barton, her daughter, Adelaide, and father-in-law, William, along with evidence that suggests the fire was started deliberately. Detective Inspector Alex Randall enlists the help of coroner Martha Gunn, but the puzzle deepens with a second house fire - the occupant, retired nurse Monica Deverill, is missing. Where is she, and what links the two fires?