Context:

Mentioned as exemplifying the theory of the Holy Grail as a secret bloodline of Christ: 'the one that is best exemplified by Holy Blood and Holy Grail.'

Context:

Mentioned as a book discussed in the previous episode alongside The Da Vinci Code, dealing with conspiracy theories about buried treasure and bloodlines

Context:

Tom mentions reading this book when he was 12-13 years old. Published in 1982, it presents the theory that Jesus came to the south of France with Mary Magdalene and established a bloodline. Written by three authors including Michael Bagent and Henry Lincoln.