A murder in Paris’ Louvre Museum and cryptic clues in some of Leonardo da Vinci’s most famous paintings lead to the discovery of a religious mystery. For 2,000 years a secret society closely guards information that — should it come to light — could rock the very foundations of Christianity.

After living in Australia for the past decade, Fitz and Judith return to Manchester in 2004 for their daughter Katie's wedding. Drinking too much at the reception, Fitz stumbles through a rambling toast, which only embarrasses the bride. Instead of spending time with his grandson, son of his married son Mark, Fitz opts to join in the investigation of a serial killer who has an apparent dislike of Americans in the wake of the U.S. Invasion of Iraq.