To track down New Zealand's monster great whites, researchers build a submersible designed to look like a shark and pilot it deep into what they believe could be a mating ground - the Holy Grail of shark science.

Dr. Craig O'Connell and Marc Payne return to where they unexpectedly filmed a juvenile great white during a past mission. Believing there's a nursery nearby, they follow the trail to a discovery that could change everything we know about great whites.