Shadows at Predator Reef

Diving into deadly waters...
 The world's largest reef exhibit is coming to the Bayport Aquarium. Frank and Joe are stoked for the unveiling of Predator Reef, a three-hundred-thousand-gallon tank that houses small sharks, rays, and thousands of colorful fish. It's also home to the aquarium's new mascot, Captain Hook - a rare and valuable, five-hundred-pound, giant sea turtle.
 But instead of a big reveal, the boys get a big disappointment: Captain Hook has gone missing, along with loads of other exotic fish. Is the aquarium the target of a sinister smuggling ring? And can Frank and Joe do damage control before they're trapped in a deadly underwater maze... with no way out?