Chilling look at prison

The penetrating “Solitary” is a sobering account of life (without parole) inside the Red Onion, a supermaximum security prison ensconced in Virginia’s Appalachians.

Home to the worst-behaving offenders in the state, most sent from other institutions for violating prison rules, the facility sequesters as many as 500 inmates, each in 8-by-10-foot cells hidden behind sky blue steel doors.

It’s the only connection with nature they’ll have save for one hour each day, when they’re permitted to get fresh air in similarly configured “rec cages.”

Given unprecedented access to the supermax facility, director Kristi Jacobson shines a spotlight on a troublingly murky corner of the criminal justice system — one in which prison officials, not the courts, determine the necessity for and the duration of long-term segregation.

Through conversations with a number of heavily shackled prisoners as well as corrections officers, the film, like Ava DuVernay’s galvanizing “13th,” addresses the questionable effectiveness of the nation’s “tough on crime” prison boom mentality of the late ’90s.

“I feel like I’ve been buried alive in the ground and everybody’s just basically walking over the top of me,” relates one of Red Onion State Prison’s longtime inmates, who might never be released back into the general prisoner population.

In Jacobson’s immersive documentary, with an enveloping sound design that unnervingly captures every echoing clang of metal on metal, the sensation is all too palpable.

“Solitary.” Not rated. Running time: 1 hour, 22 minutes. Playing: Laem-mle’s Monica Film Center, Santa Monica.