[Charles Williams] wrote a series of seven remarkable novels.

There is nothing in fiction quite like these novels. They may be described as supernatural thrillers, "popular" novels in the best sense, by a man who had something important and quite individual to say. Their plots are adventurous and breathless, their scenes sometimes entrancing and sometimes horrifying. There are pages which describe, with frightful clarity, the deterioration and damnation of a human soul, and pages who describe the triumphant struggle towards salvation.

Williams believed intensely in the impingement of the supernatural world, and he excelled in descriptions of experiences [of this kind].