Against an authentic background of deep-sea diving, John Blaine tells a fast-paced, entertaining adventure.

       To solve the mystery of a sunken oil-drilling platform, Rick Brant and his pal Don Scott must find out why their diving boat was sabotaged, fight their way through the menace of a blue shark pack, and use the technique of helium-oxygen diving from the submersible Sea Horse at a quarter of a mile below the surface of the Atlantic.

       Clues above and below the sea and cobat with a giant lobster––all figure excitingly in a nefarious plot that challenges the detective skills of Rick and Scotty.