Kaz, Dante, Adriana and Star aren’t the best divers in the world. But they’ve been chosen to spend the summer exploring the depths of the sea, in an ocean changed by a seismic event. There are only a few problems – starting with the sharks. Killer sharks. And then the fact that the people running the programme are covering up something big and mysterious. What does it have to do with a Spanish galleon full of gold that sank many centuries ago? These four kids are about to make the discovery of their lives – and put their lives in danger because of it.