In "The Atrocity Archive", Howard is given work as a field agent in finding and protecting Scottish logic professor Dominique "Mo" O'Brien, as her work – dangerously close to the point of bending reality – has triggered the Laundry's person-of-interest checks. There, Howard must contend with the Black Chamber, which in this setting was never actually disbanded, but merely went underground as the US government's equivalent of the Laundry. Howard and Mo eventually head to Amsterdam and deal with Middle Eastern terrorists also on the hunt for Mo's work. They also research the Atrocity Archive, a classified record of German efforts in World War II. In this universe, the Thule Society, a pagan and occult group formed during the defeat of Germany in World War I, actually achieved results; they were absorbed by the Ahnenerbe, which became the occult branch of the SS, and who used German mathematician David Hilbert's research (unwillingly) to attempt to gain an edge for the Nazis. The Wannsee Conference was thus an attempt to harness the occult via mass human sacrifice in the Holocaust, but it ultimately failed after Allied interference. Mo is captured by the terrorists and sent via wormhole to an alternate universe where the Nazis "did" succeed – although not in a manner they'd have preferred. In this alternate universe, the Nazis summoned a frost giant out of Germanic/Norse legend, which was actually an elder being that fed on heat and who proceeded to destroy Earth. Bob and a team of SAS agents open their own gate, infiltrate the frozen universe, rescue Mo, and leave a nuclear bomb to 'sanitise' the scene. Bob belatedly realises that the nuclear bomb is a counterproductive trap; the frost giant intends to use its power to propel it into their reality, which has far more heat to eat. Bob manages to stop the device from exploding before escaping back to his original universe.