The Holy Grail is usually considered to be a cup that was used by Jesus during the Last Supper, and also in which Jesus's blood was collected after his crucifixion. Ever since, the Holy Grail has formed the focus of epic literary and mythical quests, and in the process has led to the development of a number of conspiracy theories and ideas about the real nature and function of the Holy Grail.

These theories have formed the basis of a number of works of fiction, of which perhaps the best known is Dan Brown's The Da Vinci Code. In that book, the Holy Grail is not merely a cup, but also contains documents that explain the true story of Jesus, with a key part of the story being the claim that Jesus was in actual fact married to Mary Magdalene, and had several offspring with her.

The Conspiracy Files series lifts the lid on some of the world's most notorious mysteries, unexplained events and possible conspiracies. The narrative examines the accepted version of events, considers their veracity, and investigates the potential for conspiracy and cover-up.

There are a total of eight books in the Conspiracy Files series, with multi-book bundles comprising four books offering the best value for money.