Decision at Delphi — Helen MacInnes

Kenneth Strang sets out for Sicily and Greece on a seemingly innocent, though fascinating, magazine assignment. But even before his ship sails from New York, the atmosphere becomes charged with sinister omens.

In the course of the voyage one mysterious event follows another. After his arrival in Europe, a series of baffling encounters and the abrupt disappearance of a friend and colleague combine to intensify his mounting sense of danger.

Before long Strang joins the struggle against a monstrous and terrifying conspiracy which may affect all mankind, and long before it reaches its climax, Strang himself and Cecilia Hillard, the lovely American girl with whom he has fallen in love, are in deadly peril.