McNeil Island in South Puget Sound is the Alcatraz you've never heard of. The now-abandoned prison on McNeil operated for 136 years. Today, the island is home to the Special Commitment Center, which houses Washington state's "sexually violent predators." A collaboration between KNKX and the Washington State Historical Society, Forgotten Prison tells the stories of inmates, guards, and children who grew up on the island. The history of this forgotten place can tell us a lot about how and why we lock people up.