Riley Keough as Christine Reade in the Starz limited series "The Girlfriend Experience," which premieres Sunday. (Starz)

The irony of “The Girlfriend Experience,” which revolves around transactional relationships, is that it requires a certain level of genuine commitment.

The 13-episode limited series premieres Sunday at 8 on Starz and stars Riley Keough as Christine Reade, a second-year law student who finds herself attracted to the well-paid thrill of high-class prostitution.

The show is inspired by Steven Soderbergh’s 2009 film of the same name — a post-Spitzer scandal, recession-era project starring then-porn star Sasha Grey. (Soderbergh is an executive producer of the series, along with co-creators/writers Amy Seimetz and Lodge Kerrigan.)

Unlike most TV dramas, the episodes are just 30 minutes long. Yet I found the first few borderline intolerable. Christine starts a coveted internship at a prestigious Chicago law firm and almost simultaneously gets into the escort business after a vapid law school classmate (Kate Lyn Sheil) introduces her to the alluring lifestyle. Her initial escapades feel overwhelmingly dour, a byproduct of stilted, emotionless dialogue.

Keough plays her role with an almost impenetrable detachment that frustrates at first, but feels necessary in retrospect. She offers her client merely the illusion of emotional intimacy, and it’s just as hard for the viewer to connect with her.

Things start to get more interesting when Christine learns that one of her wealthy clients has kicked the bucket and left her a large sum of money, setting off alarm bells for the client’s family. Later, while entertaining a couple seeking a threesome, Christine has an intense reaction to the death — or to something else? It’s not entirely clear.

She tells lies — to her clients, colleagues and family — with such nonchalance that it’s tempting to diagnose her: narcissism? sociopathy? Even the series lies in a way, foreshadowing things that either don’t come to pass or happen in ways that you least expect.

Christine starts an affair with David (Paul Sparks), a partner at her law firm, while surreptitiously investigating his shady dealings in a case that also involves their colleague Erin (Mary Lynn Rajskub). As the narrative progressed, I felt increasingly anxious, a sort of pervading dread that something terrible would happen — and that even if it did, I wouldn’t care.

When Christine becomes the object of more than one man’s obsession, her double life inevitably implodes. But she comes out on top, the result of both her legal savvy and her poker-faced dealings as an escort.

“The Girlfriend Experience” takes a small break from its perpetual ambiguity when David confronts Christine about what she really does for a living. “I’m selling, yeah, but I know what I’m selling and they know exactly what they’re buying.”

Such a declarative statement is like a frying pan to the head. It’s a refreshing moment of truth.

The honesty carries into the final scene of the series, which will stay with you. Despite her successes, her new lifestyle has had repercussions in both her professional and personal life. Was it worth it? Is she fulfilled? Are we?

The Girlfriend Experience premieres with two 30-minute episodes Sunday at 8 on Starz.