The discovery of what native Mauritian diver and keen naturalist Hugues Vitry calls “shark pits” is the origin of unanswered questions about the unusual behaviour of sharks in underground caves off the coast of Mauritius. Why do dozens of sharks aggregate in these pits? Why do they act so strangely while there? In a bid to answer these questions, Hugues teams up with shark scientist Ryan Johnson, to enter the underwater world of Mauritius and explore the mysteries of the “Shark Pits”.