At first Warlock appears to be a simple film: the titular character is swept from 1691 to perhaps 1989 (the year the film was released), pursued by a hunter intent of bringing him to justice; the warlock is killed, the hunter Giles Redferne says farewell to the heroine Kassandra with a K, and is returned to his own time. There is, however, a problem: Redferne uncovered his own crypt.
Perhaps it was not a problem; perhaps no one was in the crypt, but it was simply a tomb created as an intended resting place for a man who vanished and was presumed dead. But no, someone was buried there.
Perhaps it was unimportant–something that happened in a later adjusted history which is of no consequence other than to confront Redferne with his own mortality. Unfortunately, the crypt is critical in the history that matters. It is a serious complication in the film, warranting examination.
The Warlock, who is not named even in the credits, is awaiting his elaborate execution, secured in a tower cell in Boston. Redferne, the witch hunter who put him there, has just visited, and there is some banter about Satan not having freed the Warlock–yet. Then as Redferne is leaving, there is an abrupt atmospheric disturbance, and the hunter races back in time to see his prisoner vanishing. He leaps into the indoor whirlwind after him, and he, too, vanishes.
The Warlock crashes, unconscious, through a window into the California home of Chas, where Kassandra rents a room; they stash him for the night, and after Kassandra leaves for work in the morning the Warlock kills Chas. He then finds, uses, and murders a “spiritualist” through whom he contacts the devil for instructions. He has now made a bargain, to find the three parts of Satan’s Bible and reunite them, and so become the true son of Satan who can uncreate the universe with a word. His quest returns him to Chas’ house, where the first part is hidden in what was once a communion table, but not before Kassandra has has met Redferne and delivered him to the police. The warlock curses Kassandra such that she would age rapidly, so she frees Redferne and joins him on the chase, at least until she can undo the curse.
When the Warlock gets the second part of the book, Redferne deduces the goal, and Kassandra rushes them to Boston to learn the location of the third part. It was buried with Redferne, in 1719; they recover it from the coffin just as the Warlock arrives. There is a battle in the cemetery, Kassandra delivering the fatal blow, and then barely has Redferne thanked her than he vanishes once more, leaving a fresh inscription on his tomb.
Obviously there is a lot of magic here; there are also a few difficulties that magic will not overcome. We will begin to unravel them next time.