A classic of the horror genre, Dennis Wheatley's The Devil Rides Out
pits the powers of good against the forces of evil as the Duc de
Richelieu wrestles for the soul of his friend with the charming but
deadly Satanist, Mocata. Mocata has the power to summon the forces of
darkness and--as the Duc and his friends will find--is willing to call
upon ever-increasing horror until thundering hooves herald the arrival
of the Devil Himself. The book was also made into a classic cult horror
film in 1968, starring Christopher Lee and Charles Gray.