Diana's altar

Cambridge, October 1933. Inside the old All Hallows Church on All Hallows' Eve, Doctor Adelaide Hartest bears witness to the final moments of a dying stranger.

Despite the dagger plunged into the stranger's chest, the death is ruled a suicide, compounded by a formal confession before death.

The victim, it is revealed, is known to Scotland Yard, and Assistant Commissioner Joe Sandilands is sent all the way from London to investigate.