First published in 1928, now public domain in the USA and Canada, The Missing Chums is the fourth book in the Hardy Boys series. Follow Frank and Joe Hardy as they grapple with the unexplained disappearance of their closest friends, Chet and Biff, during a motorboat trip. The stakes are high, as Baldy Turk's gang think they've kidnapped Frank and Joe and, in a letter received by the Hardy Boys' Aunt Gertrude, are demanding ransom for their return....