London, 1945. The capital is shrouded in the darkness of the blackout, and mystery abounds in the parks after dusk. During a stroll through Regent's Park, Bruce Mallaig witnesses two men acting suspiciously around a footbridge. In a matter of moments, one of them has been murdered; Mallaig's view of the assailant but a brief glimpse of a ghastly face in the glow of a struck match. The murderer's noiseless approach and escape seems to defy all logic, and even the victim's identity is quickly thrown into uncertainty. Lorac's shrewd yet personable C.I.D. man, MacDonald, must set to work once again to unravel this near-impossible mystery.