Separated by time, but united in a common destiny, modern-day PhD graduate Dr Alice Tanner inherits a house in the South of France and is haunted by dreams of 17-year-old Alais Pelletier from 13th century Carcassonne. Compelled to find out more, Alice stumbles upon an archaeological find connected to an ancient genocide which will lead her to the secrets of the Holy Grail.

Parallel storylines from the past and present unfold in the southwest of France as ancient and modern-day conspiracies are unearthed, revolving around three hidden books that hold the secret of the true Grail. Alais and those closest to her must battle to protect the secret, while in the present day Alice faces a race against time to piece together her long-buried history.