What happens when a rehabilitation program meant to cure addictions instead becomes addictive? That’s the story of Synanon, an organization that went from providing revolutionary therapy to becoming “a kooky cult,” as TIME described in 1977. The HBO docu-series The Synanon Fix, available starting April 1 streaming on HBO Max, traces the rise and fall of the organization in the 1960s and 1970s through interviews with former members and some of the children who lived in its housing. The filmmakers also obtained footage from resident amateur filmmakers and photographers from their time with Synanon.

Charles Dederich, a former alcoholic who had gotten sober through Alcoholics Anonymous, started Synanon in 1958 during a heroin epidemic in the U.S. Dederich felt people didn’t open up enough in AA and aimed to take it further with Synanon. The cornerstone of Synanon’s approach was a kind of confrontational group therapy called “the Synanon game,” where participants would scream what they really thought of one another—and then hug it afterwards. Donald Cressey, University of California at Los Angeles sociologist, described Synanon to TIME in 1961 as “the most significant attempt to keep addicts off drugs that has ever been made.”

Even after getting sober, people stuck around. Some had burned too many bridges back home, and stories of people relapsing also made some afraid to leave. By the 1960s, Synanon had become not only a treatment facility but also a communal living experiment, taking over a three-story building in Santa Monica. Mass weddings were performed. Members were encouraged to start families and took turns watching over each other’s kids. Most residents hung out in communal spaces but could reserve a private room with candles for sex by signing up on a sheet. Many shaved their heads.

Over four episodes, The Synanon Fix explores what happened at the organization and how it affected residents. Former members who share their experiences in the docu-series all emphasize how lonely they were when joining the organization, something director Rory Kennedy hopes audiences will see as a kind of warning.