Jolted from sleep by the ringing of the telephone, Imogen stumbles through the dark, empty house to answer it. At first, she can't quite understand the man on the other end of the line. Surely he can't honestly be accusing her of killing her husband, Ivor, who died in a car crash barely two months ago. As the nights draw in, Imogen finds her home filling up with unexpected Christmas guests, who may be looking for more than simple festive cheer. Has someone been rifling through Ivor's papers? Who left the half-drunk whiskey bottle beside his favourite chair? And why won't that man stop phoning, insisting he can prove Imogen's guilt?