Violets are Blue (#7) by James Patterson

Detective Alex Cross must confront his most terrifying nemesis ever- and his own deepest fears- in this electrifying new thriller from the master of suspense, James Patterson.

Alex Cross has never believed in vampires. But when two joggers are found slain in a manner that suggests a macabre ritual, he has to reconsider. Someone believes in vampires enough to have committed a series of bizarre murders that appear to be the work of one.  Local police are horrified, and even the FBI is baffled.

Cross takes on the case and plunges into a netherworld of secret clubs and role-players, a world full of poseurs and play-actor is- and someone demented enough to have crossed the line from dark ritual to real blood. At the same time, a lethal super-criminal from Cross’s past known as the Mastermind is stalking him, taunting him, and threatening everything he holds dear. Cross has never been closer to defeat, or in greater danger. In a shocking conclusion, Alex Cross must survive a deadly confrontation- only to discover at last the awful secret of the Mastermind.