For millennia, the great white shark has reigned as the ocean's ultimate apex predator. But now, a new challenger is emerging: the killer whale. Around the world, sharks are washing ashore with their livers removed with chilling precision while in the Strait of Gibraltar, orcas are targeting sailboats - ramming hulls, crippling rudders, and sinking vessels. To investigate this alarming shift in behavior, Dr. Tristan Guttridge places himself directly in the path of an orca encounter, using their attacks on boats to reveal how these predators hunt and ultimately, how they may be taking down great white sharks.

In this Shark Week whodunnit, a rare surge of highly aggressive shark attacks hit a tight-knit community off Australia's southern coast, prompting marine biologist Dr. Riley Elliott to find and tag the oceanic suspects. But when he discovers this could be a new, elusive population of sharks, he builds the world's first "chum island" to lure them in and uncover if they are the ones responsible for the attacks.

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.