#‘Smallville’ actress Allison Mack wore belly chain to show Nxivm devotion

“Smallville” actress Allison Mack wore a belly chain to symbolize her devotion to the leader of upstate sex-slave cult Nxivm, according to a former member of the group.

The new details of Mack’s involvement in Nxivm — and its twisted, master-slave offshoot where women were branded, starved and forced to have sex with leader Keith Raniere — were revealed in HBO’s new documentary series “The Vow,” which debuted last week.

One of the club’s defectors, “Star Wars” actress Bonnie Piesse, recalled taking a walk with an emaciated Mack before she left the group.

“She was kind of at her skinniest, she looked like her backbones were sticking out,” Piesse said in the doc. “But I confronted her and said, ‘I think you’re sick. You’re not eating, like there’s a problem, you need to address it and start eating.’”

The young actress replied that Raniere was measuring her calories, and he’d said that as long as she got her period, she was fine, Piesse recalled.

Then, she dropped a bombshell, according to Piesse.

“And then she says that she’s made a lifetime vow to Keith and I think she said it was a vow of devotion and she lifted up her shirt and showed me her belly chain,” she recalled. “She said, ‘And this is to symbolize the vow that I’ve made.’”

Prosecutors said Mack served as a high-ranking member of the group, known as DOS, and was tasked with recruiting young women as “sex slaves” for Raniere — who had them branded with his initials, forced them to turn over nude photos as “collateral” and sleep with him at his whim.

Piesse — who starred as the young Aunt Beru in “Star Wars: Revenge of the Sith” — and her husband, filmmaker Mark Vicente, fled Nxivm in 2017 after finding out about the secret sex sorority.

The documentary series, which airs Sunday, features extensive video recordings taken by Vicente, offering viewers an inside look into the disturbing cult that billed itself as a self-empowerment group in upstate New York.

Piesse said she was blindsided by Nxivm’s evil side.

“I certainly didn’t understand it, but I didn’t see the darkness that was really there at that point,” she said. “Allison saw Keith as like a guru, a spiritual master and she was very committed to the mission.”

Raniere, the self-styled self-help guru referred to as “Vanguard” by his followers, was convicted last year of racketeering and sex trafficking following a sordid trial in Brooklyn federal court.

Other Nxivm members — including Mack and Seagram’s heiress Clare Bronfman, who bankrolled the group — have pleaded guilty to their involvement in the cult.

Bronfman faces up to 27 months in prison at her sentencing on Sept. 30.

Prosecutors, meanwhile, want Raniere sentenced to life, noting his lack of remorse and recent offer of a $25,000 reward to find holes in his case. He’ll be sentenced on Oct. 27.

Mack’s sentencing was postponed last year and a new date has not yet been set.