While TOM KANS, world renowned expert on codes and symbols, is in Paris to give a lecture, he receives a late phone call from the Paris police informing that the manager of the Louvre, JAN PIERRE MARIE, has been murdered in the famous museum and next to the body, the police has found a monogrammed code. Tom Kans is asked to help decipher the code and thus begins a one night adventure, together with SOPHIE MONE, a leading cryptologist and the niece of the murdered manager, as the follow a series of clues embedded in the art of Leonardo Da Vinci. The mind twisting one night adventure eventually leads to the Priory of Sion, a secret society whose members included Isaac Newton, Botticelli, Victor Hugo, Da Vinci, as well as Jan Pierre Marie, who, it is discovered, had sacrificed his life to protect the great secret of the Priory of Sion: The final resting place of the Grail. Pursued by the Paris police, and a fanatical assassin of the Opus Dei, Tom and Sophie follow the trail of clues hidden in religious symbols and works of art to through London and Paris finally uncovering the mystery of the Grail.
