Gyles Brandreth writes a mystery series based on the fictional adventures of Oscar Wilde and Sir Arthur Conan Doyle.  Oscar Wilde and the Vatican Murders is the fifth book in the series.

Oscar Wilde and the Vatican Murders opens in 1892, as an exhausted Arthur Conan Doyle retires to a spa in Germany with a suitcase full of fan mail. But his rest cure does not go as planned. The first person he encounters is Oscar Wilde, and the two friends make a series of macabre discoveries among the letters—a finger; a lock of hair; and, finally, an entire severed hand.

The trail leads the intrepid duo to Rome, and to a case that involves miracles as well as murder. Pope Pius IX has just died—these are uncertain times in the Eternal City. To uncover the mystery and discover why the creator of Sherlock Holmes has been summoned in this way, Wilde and Conan Doyle must penetrate the innermost circle of the Catholic Church and expose the deadly secrets of the six men closest to the pope.