It’s a legendary disappearing act—and one of the most complex prison breaks in history. On June 11 1962, Frank Lee Morris and brothers John and Clarence Anglin managed to break out of fortress-like Alcatraz Island federal penitentiary and brave the rough, freezing waters of the San Francisco Bay in a handmade raft. Their masterful plan employed contraband tools, dummy heads made from soap and human hair, life jackets sewn from raincoats, and an ingenious combination of opportunism and careful planning.

Today we know exactly how they made it out of the cell block and down to the water’s edge. But nobody knows what happened next.

Despite one of the largest manhunts in U.S. history, Morris and the Anglins were never seen again, and for nearly 50 years people have assumed the trio drowned.

But the US  Marshals aren’t convinced, and if anyone can find the elusive Alcatraz escapees, they can. America’s oldest federal law enforcement agency is charged with tracking down three of the country’s most elusive fugitives. The Marshals never give up on an open case—and for Deputy US  Marshal Michael Dyke, the Alcatraz case is very much open for business.

We’ll go inside the Marshals’ investigation, into this decades-old case, and learn what striking new evidence has convinced Michael Dyke that at least one of the fugitives may have survived the escape. It’s a revelation that overturns basic assumptions about this infamous case. Retired and active deputy marshals will also share their war stories, revealing for the first time the most incredible, tantalizing, and strangest leads they’ve chased down over the years. Hear about two escapees attending a family funeral dressed as women, bodies allegedly buried deep in the Seattle woods, and a set of exhumed human remains that may just belong to mastermind Frank Morris.

Would the bay’s strong tides really have swept the prisoners out to sea? One coastal engineer with the US Army Corps of Engineers doesn’t think so. Is it true the prisoners’ raft was never recovered? New evidence calls that into question. More than a fascinating look into this legendary prison break, this Undercover History hour is a revealing look at the US Marshals and the complex work involved in their search for some of America’s most notorious fugitives.