The Baker Street Irregulars are on the case, assisting the master detective Sherlock Holmes with a most compelling mystery. With the help of the BSI, Holmes has set an elaborate trap to capture Professor Moriarty and dismantle his crime organization, at last! But Moriarty has his own plans. In their latest adventure, the Irregulars face the greatest challenge of their careers. The quest will take them, for the first time, out of England and on a thrilling chase through continental Europe. Will Holmes and the Irregulars succeed? Or will they fall prey to the most dangerous man in all of England?

Tracy Mack is the author of two celebrated novels: BIRDLAND, a Book Sense Top Ten Book, a Sydney Taylor Award Honor Book, and an ALA Best Book for Young Adults; and DRAWING LESSONS, a Booklist Top Ten First Novel and a Teen People NEXT Award Finalist. Michael Citrin is an attorney and has been a Sherlock Holmes fan since he was a young boy. Together they have written the Sherlock Holmes and the Baker Street Irregulars series published by Orchard Books. Tracy and Michael are married and live in the Berkshire Hills of western Massachusetts with their three young children. Tracy Mack is the author of two celebrated novels: Birdland, a Book Sense Top Ten Book, a Sydney Taylor Award Honor Book, and an ALA Best Book for Young Adults; and Drawing Lessons, a Booklist Top Ten First Novel and a Teen People NEXT Award Finalist. Michael Citrin is an attorney and has been a Sherlock Holmes fan since he was a young boy. Tracy Mack and Michael Citrin are married and live in the Berkshire Hills of western Massachusetts, with their two young children.