"To the public, Britt St.Vincent is a great Grand Prix racing driver. To the Pentagon, Britt is a dangerous renegade scientist who quit their frighteningly effective mind-control research project. To a vast secret organization known as Mero, Britt is a vital agent in a global struggle against the dark occult forces menacing humanity. The Door opens to mind-warping horror when Britt St.Vincent searches amid the ancient ruins of Stonehenge for the key to the unknown evil invading the world. In this eerie place women are turned into helpless instruments of sex, men become robot-like creatures of violence, and giant computers are given terrifying psychic powers. And now Britt must go where no man has ever gone before to make a desperate last stand against humankind's ultimate Enemy."
Used availability for John F Rossmann's The Door