Richard Hannay is introduced to Dr. Nils Larssen and his daughter Kirsten by Lord Hurst, the owner of a Chemicals business which operates out of Hurst Grange, a manor house in the English countryside.

Dr. Larssen is working on a serum which will produce a vaccine against 'the terrors of the earth' - typhus, tuberculosis and cholera, which may be needed in the event of germ warfare in any conflict with Germany. The idea is to produce vast amounts of the vaccine which Lord Hurst is prepared to back and then to market.

Also working in the laboratory at Hurst Grange is Edgar Voce, a German agent. Voce approaches Otto Von Schwabing, the murderous teutonic villain who is responsible for most, if not all of the treacherous activity of The Black Stone, the German Terrorist Organisation. Voce tells Von Schwabing that he is producing vaccine for German use in the event of warfare, and Von Schwabing keeps his ear to the ground.

Dr. Larssen becomes suspicious of Voce, and is poisoned by him, d