Frank and Joe Hardy have been invited to go on trip to the Florida Keys to help save sharks and work alongside Lookout Shark Lab's Dr. E. Ella Edwards, one of the world's foremost marine biologists, to take part in a conservation mission at the Bayport Aquarium. But the trip's purpose is suddenly sidelined when a Dr. Edwards goes missing and the story is that the her 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?