- Henry Lincoln continues investigating Rennes-le-Château, moving from screenwriting to full-time research.
- Lincoln meets Richard Leigh and Michael Baigent, forming a trio that will popularize the conspiracy.
- The third BBC Chronicle episode "The Shadow of the Templars" airs in 1979, focusing on Lincoln's personal quest.
- Lincoln, Leigh, and Baigent meet Pierre Plantard, who claims to be Grand Master of the Priory of Sion and a Merovingian descendant.
- Plantard hints at a spiritual treasure and a secret bloodline, refusing to reveal the order's future plans.
- Lincoln discovers a pentagonal geometry in the landscape around Rennes-le-Château, linking it to Venus and Mary Magdalene.
- The book "The Holy Blood and the Holy Grail" is published, arguing that Jesus married Mary Magdalene and had children, founding the Merovingian line.
- The Priory of Sion is portrayed as protecting the bloodline, with the Holy Grail reinterpreted as royal blood (Sang Raal).
- The conspiracy evolves from a treasure hunt to an apocalyptic vision of a new world order led by the Merovingian heir.
- Despite lack of evidence, the theories gain widespread popularity, influencing later works like "The Da Vinci Code".