Widely regarded as one of the finest occult thrillers ever written, and almost certainly his most famous work, the Devil Rides Out is a rollercoaster of an adventure, set in post WW1 England, and chronologically the third in sequence to feature "Those Modern Musketeers", De Richleau, Simon, Richard and Rex.
Concerned with their friend's absence, The Duc and Rex pay a visit to Simon's house in North London, where they come across a bizarre gathering of strangers. Suspecting foul play, the Duc ignores Simon's claims that he has joined an astrological society, and quickly discovers that he has in fact, joined a satanic sect, led by the powerful Mocata. What follows is a game of cat and mouse as Simon is pulled between the powers of light and darkness in a battle of the astral plane. Dinner at the Ritz, fine wines, brandy, cigars and vintage sports cars are all part of a rich backdrop in what amounts to a phenomenally well researched and gripping thriller. Stand out scenes include the sacrifice to Satan on Salisbury Plain, the car chase, the mesmeric words of De Richleau and of course, the infamous night in the Pentangle, where the friends encounter the Angel of Death himself.
The book was to inspire the sixties Hammer version, and though the film was not quite up to the quality of the original, it did feature a great performance from Christopher Lee, and of course, the most chilling line captured on film by the powerful Charles Gray: "I won't be back, but something will."