December 1940. Down Street underground station, in the heart of London's Mayfair, is now a secret retreat for Prime Minister Winston Churchill and his cabinet from the relentless air raids overhead. In this supposedly secure location, the body of a woman is found, stabbed in the heart. The victim, fortune-teller Lady Za Za, did not see this one coming. Chief Inspector Coburg and Sergeant Lampson are called to investigate but whispers of treason and corruption succeed in muddying the waters of the case. As the pressure rises and more victims come to light, Coburg and Lampson are on dangerous ground, with a devious killer on the loose.