This story opens with Lionel Rackstraw, a publishing executive, returning from lunch to find the telephone bell in his office ringing. As he picks up the receiver he notices on the floor the legs of a man protruding from under his knee-hole desk. Taking the man for an engineer fixing a wire he asks how long he will be. Receiving no reply he discovers that the legs are those of a corpse.

In view of the above, a reader who is not acquainted with the work of Charles Williams might well suppose that he is about to enjoy a straightforward murder mystery. But far from it, the murder is a mere incident in a far more sophisticated type of novel.

Among writers about the supernatural Charles Williams stands apart. He is a true mystic and does much more than simply tell a story: he delves deeply into the impulses to do good or evil that affects men’s minds.

The central feature of the present tale is the Holy Grail – the goblet from which Jesus Christ drank at the Last Supper. Tradition has long asserted that Joseph of Arimathea brought the Grail to England on one of his merchant voyages and left it at Glastonbury, where it was deeply revered for its miracle-working powers by King Arthur’s Knights of the Round Table, but in the dim past the Grail disappeared.

In this story the Grail turns up again at the village of Fardles and is in the care of a benign and charming Archdeacon. A big house named ‘Cully’ near the village is owned by Mr. Gregory Persimmons, the retired father of Stephen Persimmons, the present head of the publishing firm. Persimmons senior has a very erudite crony, Sir Giles Tumulty, and both are deeply interested in Satanism. They plan to get possession of the Grail, and the former also has designs on Lionel Rackstraw’s young son, Adrian, his intention being to offer the boy to the Devil at a Sabbat.

Lionel’s wife, Barbara, is bewitched; her son willingly becomes more or less the ward of Gregory Persimmons and the precious Grail changes hands several times.

The scene moves to a run-down chemist’s shop in a disreputable street off the Finchley Road. It is owned by a sinister Greek who has long been a practitioner of the Black Arts and serves a Satanic being referred to as the Priest-King.

The police, who have been investigating the murder in the publisher’s office, learn that it occurred in connection with the struggle for possession of the Grail, but are baffled by supernatural disturbances that take place in the neighbourhood of the chemist’s shop.

This strange war between a group of Satanists and the Powers of Light represented by the Archdeacon, Lionel and a Catholic Duke cannot possibly fail to intrigue any reader.