The action, adventure, and mystery-something story, «The Mercer Boys' Cruise in the Lassie», was written by American author Capwell Wyckoff (1903-1953), telling the adventurous cruise on a newly acquired sloop, with bandits, hairbreadth Harry escapes, and pretty unrational procedure. Don and Jim Mercer and their buddy Terry Mackson set out in their sloop, Lassie, for a visit to Mystery Island, in search of adventure and fun.