Vampires, werewolves, mechanical men—it's all in a day's work for Harry Challenge, agent of the Challenge International Detective Agency! This volume collects both Harry Challenge novels by Ron Goulart, The Prisoner of Blackwood Castle and The Curse of the Obelisk.

"Ron Goulart's most recent original P.I. creation, HARRY CHALLENGE is a field operative for the Challenge International Detective Agency, the family business. Receiving his assignments by mail and telegram from his nearly-estranged father, Harry bounces around early-20th-century Europe, usually accompanied by stage magician The Great Lorenzo (whose abilities may not all be just sleight-of-hand). Intrepid girl reporter Jennie Barr is often on the same trails as Harry, alternately aiding and competing with him in cracking the cases...and as the mysteries may involve werewolf assassins, clockwork swordsmen and the odd vampire or two, Harry can sometimes use all the help he can get!"—Thrilling Detective