For decades, rumors have swirled about massive,15 to 20-foot mako sharks patrolling the deep waters off Southern California. Long dismissed as fishermen's tales, new footage, along with a recently published photo capturing a mako that appears to push 15 feet, is now forcing scientists to rethink everything they know about these oceanic apex predators. Marine biologist Tristan Guttridge, alongside conservationist Kendyl Berna and shark tagger Keith Poe, leads an investigation to determine whether the world's biggest mako is real - and hunting in the coastal waters of Santa Catalina.