The New York Times bestselling Mysterious Benedict Society series returns for a triumphant fourth adventure! After starring in three adventures, the inimitable quartet of Reynie, Sticky, Kate, and Constance haven't had a mission together in some time. But with the arrival of a new Society member - and a new threat - they must reunite to face dilemmas more dangerous than ever before, including the return of the villainous Mr Curtain and his Ten Men and a formidable enemy with a mystifying ability to track their every move.