Brother detectives Frank and Joe dive deep into the Florida Keys to find a missing person in the twenty-first book in the thrilling Hardy Boys Adventures series.Frank and Joe Hardy have been invited to take part in a conservation mission by a marine biologist at the Bayport Aquarium. The boys get to go on an all-expenses paid trip to the lush and beautiful Florida Keys to help save sharks! But the trip&;s purpose is suddenly sidelined when a paddle boarder goes missing and rumors start that the disappearance is the result of a shark attack. After spending so much time learning about the local shark population, the Hardy Boys aren&;t buying the story. It will take all of Frank and Joe&;s recently acquired knowledge about sharks and their habitat to solve this case. Will they be able to discover what&;s really going on before it&;s too late?