The whole point of "Mrs. Fletcher" is that the eponymous character is not, in fact, supposed to be Mrs. Fletcher.

in HBO's new miniseries (Sunday, 10:30 EDT/PDT,★★★ out of four), Kathryn Hahn's sexually adventurous empty nester is Eve Fletcher, but she hasn't been married to Mr. Fletcher for a decade. Her battle to be a "Miss" is part of her battle to be her own person, not solely identified as a mother to an ungrateful son or an ex to a seedy husband. That journey towards self-actualization involves putting herself above her son, meeting new people and exploring new experiences. And also a lot of porn, masturbation and sex.

The series, adapted by Tom Perrotta from his own novel, begins on the eve of Eve's son Brendan's (Jackson White) departure for college, and the dynamic between mother and son becomes immediately clear. She is doting, adoring and does everything for him. He is self-obsessed, ignorant, inconsiderate and a bully, as he demonstrates at a last-hurrah high school party by destroying the phone of his outcast classmate Julian (Owen Teague).

After Eve and Brendan part at the dorm elevator, the series follows each in their new, solo lives. Eve is initially devastated by loneliness, while Brendan is thrilled to take college by storm the way he did in high school. As the series progresses, Eve begins to thrive as she discovers the world of online pornography and also makes new friends through a community college writing course, in which 19-year-old Julian is a fellow student. But Brendan begins to falter as he realizes that he was a sheltered, privileged kid who is incapable of taking care of himself or surviving in a world that doesn't worship him.

The series showcases Hahn at her absolute finest, excelling with a character so intimately perfect for her you might have to remind yourself "Fletcher" was a novel before the actress ever became a part of the story. She is wholly devoted to the role, including the sexuality and nudity required for a character so fascinated by intimate relations. Her acting sometimes rises above the material, rescuing a few moments of sloppy pacing and questionable narrative decisions.

As wonderful as Hahn and most of the supporting characters we meet in the writing class are, a major problem in the series is that, in addition to being a rather abhorrent human being, Brendan's story isn't nearly as compelling as his mother's. While the story of a privileged white man being slapped in the face by reality has some juice, the series only skims the surface of the ideas behind it, and every moment spent with Brendan is one that could have been spent more happily with Eve. The series also never fully addresses how a seemingly evolved and tender mother could have raised such an ignorant, aggressive and cruel son, his flagrant daddy issues aside.

However, Brendan is welcome when he's more directly involved in Eve's story, flitting in and out of her life at intervals that help push her into self-discovery. His role in the finale is so exquisite and astonishing, it almost makes it worth having him around for all seven episodes.

For a self-contained story, the ending of "Fletcher" is shockingly abrupt and open-ended. It's a hard trick to pull off, and Perotta does it beautifully. The limited series is refreshingly succinct and poignant throughout.