This new hour heads out to deep water to understand the battlefields beneath the surface, where death comes from every direction and escape is impossible. It’s where rarely seen, little known, large sharks compete for every scrap of food … and where we’ll capture a secret, scary, shark society – for the very first time.

Focusing on the remote waters off New Zealand’s North Island, we film right in the middle of a dramatic shark feeding frenzy, with experts explaining swarm dynamics and hierarchy. We also film extraordinary swarm behaviour in other locations, including investigating why 45 shark species periodically congregate off the coast of Colombia when there’s little food and they’re not mating.