Da Vinci Code, Foucaults Pendulum,

all linked together through D.O.U.O.S.V.A.V.V.M.

"But veteran code-breakers from Bletchley Park, the former Second World War intelligence centre-turned museum in Buckinghamshire, now say the code is likely to stand for "Jesus (As Deity) Defy", a message from a sect called the Priory of Sion, a secret order with similar beliefs to the Knights Templar. Both sects were held to be heretical, notably by the Church of England, because they considered Jesus to be an earthly prophet, not a heavenly one."