When, one dark night in November, Prince Ludovico Ruspanti fell a hundred and fifty feet to his death in the chapel at St. Peter's, Rome, there were a number of questions to be answered. Inspector Aurelio Zen finds that getting the answers isn't easy, as witness after witness is mysteriously silenced - by violent death. To crack the secret of the Vatican, Zen must penetrate the most secret place of all: the Cabal.