Both of the stars of Stay The Night are nearly unrecognizable the first time we see them on screen in this four-hour miniseries based on a case that made news in 1986. As a Georgia housewife and mother, Jane Alexander wears her hair dull brown and choppily cut; her mouth droops, her eyebrows arch in some mixture of weariness and hopefulness. As Blanche Kettmann, the mother of a young man drawn into romance and murder with an older woman, Alexander looks like Edith Bunker after a standoff with Archie.

Barbara Hershey plays that older woman, Jimmie Sue Finger, and if the actress wanted a change of pace after playing the prim, mousy murderer in 1990’s A Killing in a Small Town (for which she won an Emmy), she has certainly succeeded. In platinum blond hair and a thigh-splitting miniskirt, Hershey’s Jimmie Sue is first glimpsed in Stay at a party, where she’s dirty dancing with a teenage boy half her age.

Is it any wonder that 18-year-old Mike Kettmann (The Long Road Home‘s Morgan Weisser), gazing at Jimmie Sue from across the crowded party, is attracted to this mature bombshell? Attracted isn’t even the word — watching Mike watch Jimmie Sue, we can almost see the hormones exploding under his skin like firecrackers. Of course, the fact that Jimmie Sue is the mother of Angela (Judith Jones), the girl Mike has just started dating, only makes the situation hotter for him. Screenwriter Dan Freudenberger (Do You Know the Muffin Man?) may be following the facts of the real lives in this case, but he and director Harry Winer (When You Remember Me) have also tapped into something more universal: Lusting after your girlfriend’s mom is a grabber of a prime-time fantasy.

In fact, the entire first half of Stay the Night is a grabber, with a swift, occasionally delirious pace unusual in a four-hour TV drama. This section of Night details the way Jimmie Sue seduces Mike and then goads him into killing her husband, Terry Finger (Scott Higgs). Jimmie Sue makes a bold play for Mike; after catching him necking with Angela, she demands, ”If you kiss her, don’t kiss me; if you kiss me, don’t kiss her.” Perhaps addled by her syntax, Mike wanders off into a bathroom. But Jimmie Sue follows, plants a big smooch on his trembling mouth, and from that point on, it’s bye-bye Angela.

Once the polite, sensitive, but oh-so-het-up Mike makes it clear that he is more interested in Jimmie Sue than her daughter, the new couple delights in scandalizing their small Southern town, to the mortification of Mike’s parents (Alexander and Earl Hindman). When Blanche asks Jimmie Sue to leave her son alone, this girl-woman says she can’t help it: ”He makes me feel 16 again,” she sighs. Looking at the grim, uptight Blanche, Jimmie Sue murmurs, ”Don’t you ever wish you could just go back and start over? Like, um, erotic time travel?”

Pretty soon, Jimmie Sue is pulling Mike into the woods and cooing, ”Take off your jeans”; Mike, more the romantic type, is blurting adolescent gush like, ”You’re a beautiful rose…You need a man who can understand how to treat a delicate rose… ” Stay the Night captures both the intensity and the foolishness of their affair, and keeps us intrigued: Does Jimmie Sue really love Mike, or is she just using him? It’s only a matter of time before Jimmie Sue is telling her young lover that she and Angela have for years been abused by her husband, and letting Mike know she has a gun he can use anytime. Bang, bang.

The first half of Stay the Night concludes with Mike in court, sentenced to life for murder. As the young man is led from the courtroom in tears, Blanche vows to find new evidence that will set Mike free, or at least convict Jimmie Sue. We know that the rest of the mini-series will follow Blanche’s efforts to prove that Jimmie Sue coerced Mike, but the prospect isn’t an exciting one — we’ve seen the passion, the crime, and the punishment; what more do we need?

Well, writer Freudenberger needed to fill another two hours to stretch this into a sweep-period miniseries, and so the tone of Stay the Night shifts surprisingly during its second night — it becomes the story of the relationship Blanche cultivates with Jimmie Sue. Blanche starts out deviously, hoping to befriend Jimmie Sue and then trick her into admitting her own complicity in the murder. (Blanche receives support in this plan from a homicide detective played by Fred Dalton Thompson [Cape Fear], doing his usual charming Andy- Griffith-as-a-big-growly-bear routine.)

But Jimmie Sue proves to be a charmer. While she’s still determined to implicate her, Blanche is shocked to realize she actually likes this lonely, confused woman. Here is where Night goes slack, as Jimmie Sue becomes a sort of lovable nut while Blanche becomes, very improbably, a steel-nerved avenger. And the movie’s supposedly surprising ending seems, instead, inevitable.

The acting throughout Night, however, is consistently excellent, with both actresses equal to the twists in the plot. And Weisser, who first perfected the role of sensitive-but-never-wimpy teenager in the terrific 1990 TV movie Home Video, makes an ideal combination of fall guy and killer. The first night of Stay the Night rates an A and the second a C, averaging out to a B.