PLOTTING: Patricia Arquette plays prison worker Tilly, who becomes entangled with two inmates in ‘Escape at Dannemora,’ which is based on a true story.

“Escape at Dannemora” often feels like you’re the one doing time.

The seven-part, seven-and-a-half-hour series debuting Sunday on Showtime, tells the true story of two prisoners’ escape from the Clinton Correctional Facility in New York in 2015. The prison break received nationwide attention —  especially from the tabloids (“Shaw Skank!”) —  because a female prison employee helped them escape, supplying them with tools in exchange for sex.

“Escape’s” greatest coup is its casting: Academy Award-winner Patricia Arquette (“Boyhood”) is fascinating as Joyce “Tilly” Mitchell. Needy, whiny, with forever pursed lips, she’s nobody’s idea of a femme fatale. 

When the story opens in January, months before the escape, she’s already having sex with one of the inmates, David Sweat (Paul Dano, “Little Miss Sunshine”), in a supply closet. 

It might be the worst kept secret in the tailor shop she manages, one that amuses another lifer, Richard Matt (Academy Award-winner Benicio del Toro, “Traffic”). He practically runs the prison with the approval of a guard (David Morse, “Blindspot,” “The Green Mile”). 

When a complaint gets David booted from his job —   and out of Tilly’s orbit —  Rick moves in, manipulating Tilly into sexual dependence and then using that to get her to smuggle tools to him, all with the promise that she will join him and David in Mexico to start a new life.

With his hair slicked back, del Toro resembles a cross between a Dick Tracy villain and a gang member from “West Side Story.”

The sixth episode is a flashback  that delves into the pre-prison lives of this bizarre, um, devil’s triangle, and chases away any affection you might have for them. The men are killers. Tilly is a monster in her own right, evicting her first husband from their child’s life so she could be with her second husband, Lyle (Eric Lange, “Narcos”), who seems to have an IQ just above freezing.

In the supporting cast, Bonnie Hunt (“Cheaper by the Dozen”) is a stand-out as New York state Inspector General Catherine Scott, tasked with investigating the breakout.

Arquette’s Tilly is the centerpiece of this series, a woman forever restless and always making the wrong decision. 

Lifetime got to this story first last year with “New York Prison Break: The Seduction of Joyce Mitchell,” with Penelope Ann Miller. That was only two hours. 

Ben Stiller, best known for his comedic turns in such films as “Meet the Fockers” and “Zoolander,” directs all seven episodes and he’s competent and maybe too thorough. The series could have easily been trimmed by a third.

There are only so many times you can watch a man bang away at a wall.