Jolted from sleep by the ringing of the telephone, Imogen fumbles 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 died in a car crash two months ago - she may not be adjusting to widowhood very well, but Imogen certainly didn't murder him.
As the nights draw in, Imogen finds her home filling up with unexpected Christmas guests - but they may be looking for more than just holiday 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 Imogen, insisting he can prove her guilt?