In February 1980, just out of his latest stint in California’s juvenile prison system, 19-year-old Kenneth Hartman, drunk and stoned, punched and stomped a homeless man into unconsciousness in a park outside Long Beach. Arrested the following day, Hartman overhears that his victim is dead and enters a new category of criminal: murderer.

About halfway into the process, the jailer told [another officer] I was being booked for beating someone to death. The blanching of the skin, the curious way fear dilates pupils, the slight drawing away: I saw all this for the first time. I felt a surge of power run through me. I had reached the pinnacle of antisocial behavior; I had killed with my bare hands.

Hartman’s been in prison ever since, on a sentence of life without the possibility of parole. His memoir, Mother California: A Story of Redemption Behind Bars, traces his gradual conversion from a monstrous “coiled spring of hostility” to a compassionate prison-reform activist who’s deeply ashamed of his crimes.

It’s a gripping and often harrowing story. His three-decade saga takes him through a half-dozen prisons, and much of his early time is spent in solitary. His descriptions are sharp and, remarkably, suffused with dry wit. He recalls the greeting a lieutenant gave his group of newcomers at Folsom Prison: “If you try to escape, we’ll kill you. If you put your hands on one of my guards, we’ll kill you. Other than that, we don’t give a shit what you do to each other.”

It is, of course, hard to trust a prison memoir. One thinks of Jack Henry Abbott: His letters from prison, published in 1981 as In the Belly of the Beast, seduced Norman Mailer into helping him get paroled; six months later, he was back in jail for murder. But Hartman’s unsparing introspection—along with his gift for moral shading—makes his account of self-reinvention convincing. There’s no self-pity here, none of the cunning charm of the sociopath. About the man he murdered, Hartman says: “I’m determined to remake myself, as it’s the only possible way I can even begin to atone for stealing his life.”

His transformation begins with Anita, a fiery woman who answers the phone when he calls a lawyer’s office on a fellow inmate’s behalf. After many conversations, she visits and tells him, “You are wonderful.” They marry and, thanks to conjugal visitation rights that California has since abolished, have a daughter. He forsakes drugs, enters group therapy, and begins devouring books. He ultimately concocts the Honor Yard Program, for “those of us who simply want to do our time, away from the bullshit and the madness,” which the warden at California State Prison, Los Angeles County, where Hartman remains, initiates in 2000.

Mother California isn’t a plea for freedom or forgiveness; Hartman knows he’s not getting out. All he apparently wants, beyond the humane treatment of prisoners and his dream of teaching philosophy, is some respect. He’s earned mine.

Lawrence Levi is a co-author of The Film Snob’s Dictionary.