The story starts as a murder mystery but quickly becomes the story of the hero and heroine solving clue after clue in their search for the Holy Grail whilst being pursued by the police who are trying to catch them and members of a hard-line Roman Catholic group (Opus Dei) trying to stop them finding the Grail before they do.

The book is a novel – no one is claiming that the storyline is anything but pure fiction but it does contain a number of anti-Christian statements about Christ, the Bible and its history and the Church. By the Church the book really means the Roman Catholic Church but most of what is said is also relevant to evangelical teaching about these things.