"How do I solve homicides with no bodies, no evidence and no forensics?" asks special investigator Karsten von Hoesslin, who found himself in such a predicament while trying to piece together the truth behind a quadruple murder at sea. In 2014, cellphone footage from a mysterious address in Fiji goes viral. The 10-minute clip shows four men clinging to wreckage in the middle of the ocean. Then, one by one, the men are brutally shot and killed. No one knows exactly where it happened, why, or who committed these crimes. In "Lawless Oceans," von Hoesslin relentlessly pursues clues and angles, tracks down and interviews eyewitnesses, material witnesses and families of the victims, and seeks the support of fellow experts to determine who is responsible. Along the way -- painting a dark, grim picture of lawless international oceans -- he encounters drug smuggling, people trafficking, illegal fishing, and piracy.