Phil Torres and Heather Amaro travel 5,000 miles west of the U.S. to the remote Marshall Islands, home to the world's largest shark sanctuary, where apex predators are exhibiting highly aggressive behaviors and erratic swimming patterns. Between 1946 and 1958, the United States military detonated 67 nuclear bombs around the island, raising questions about their lasting impact on marine life. Now, the team dives into these dangerous waters to investigate reports of "mutant" sharks and uncover whether atomic blasts could be to blame.