Murder Live! (Sun. (9), 9-11 p.m., NBC) Filmed in Burbank by Von Zernick/Sertner Films in association with NBC Studios. Executive producers, Lisa Demberg, Peter Horton, Robert M. Sertner, Frank Von Zerneck; producers, Randy Sutter, Karen Moore; co-producer, Ted Babcock; director, Roger Spottiswoode; writer, Chris Bertolet; camera, Jeffrey Jur; editor, Dominique Fortin; production designer, Donald Lee Harris; music, Gary Chang; casting, Susan Glicksman, Fern Orenstein. Cast: Marg Helgenberger, David Morse, Peter Horton, Teri Garr, Christine Estabrook, Lauren Tom, Eloy Casados, Neal McDonough, John O’Hurley, Michael Cullen. Jarring, disturbing and spectacularly ironic television, “Murder Live!” is “Dog Day Afternoon” for the ’90s, a potent, outlandish nuclear warhead of a thriller that explodes onto the screen with a demented blend of force and farce. Expertly directed by Roger Spottiswoode and filmed with an artfully jerky, quick-cut intensity by cinematographer Jeffrey Jur and his team, the film’s claustrophobic premise holds up phenomenally well over its two hours. Terror hits a soundstage. Film at 11. And at 11:01. And 11: 02. The darkly comic sendup of the trash-talk genre is bolstered by some sparkling acting from “ER’s” Marg Helgenberger and a frightening piece of work from “St. Elsewhere” vet David Morse, who has grown to become a remarkably effective heavy. Helgenberger is Pia Postman, the shallow, vain, driven host of her own trash-talk hour. As we pick up the story, Postman is about to host a theme show about the trauma of rape in the wake of the suicide of a young woman whom Postman outed on her show as the victim of a gang rape. So Postman — a human glob of makeup and hair dye, smart suits and mock compassion — has just compounded her exploitation of the victim by running a tape of the woman leaping to her death from a building as a means of setting the mood for the upcoming broadcast. What she doesn’t know is that the woman’s grieving father, Frank McGrath (Morse), is lurking in the audience. He strides onstage as things begin, brandishing a pistol. He proceeds to take both the show and the studio audience hostage, explaining that he has planted a bomb in the studio and demanding that the broadcast remain on the air to record live the surreal events. This, of course, requires a measure of artistic license, given that talkshows of this ilk are shot on tape and never shown live. But OK. As bedlam reigns, McGrath demands that the show avoid breaking for commercials. He explains with hostile simplicity that he intends to harm only host Postman, planning to extract aconfession out of her for killing his daughter and then executing her live, coast-to-coast. While a version of this live-TV premise surfaced in “Natural Born Killers,” and certainly nothing would surprise any of us after O.J. Simpson’s slow-speed Bronco chase, “Murder Live!” takes the concept to its absurd extreme. The core film takes much of its sensibility from the extraordinary 1975 drama “Dog Day Afternoon.” Here, we have crowds gathering outside a TV studio as police and SWAT units (led by a terrifically cool Peter Horton, who also executive produces) plot their strategy to keep McGrath from going nutzo and to diffuse the bomb before it’s detonated. But what gives “Murder Live!” its true edge is the subtle, warped, revealing details that flow through Chris Bertolet’s piercing script. For instance, an oft-absurd crawl runs across the screen at regular intervals (aimed at the audience watching the drama unfold at home). One, alluding to the fact that a baseball playoff game is that night, notes, “We will keep you apprised of the playoff game until the hostage situation is resolved.” Sure enough, moments later, a picture of the ballgame appears in a box at the upper right of the screen as McGrath is screaming something at a hostage. It would never happen, you say? Remember what NBC did on Bronco-chase night with the NBA Finals? Too, when one of the hostages is released, we see her looking star-struck to meet the cop (Horton) doing the negotiating. Another illustration of TV’s capacity to confuse the preposterous with the pertinent. And early on, it’s fascinating to see how the host and a therapist on the would-be panel try to treat their captor as they would a troubled guest. “Murder Live!” pushes on to a heavy conclusion. And along the way, it is a tad too over-the-top for its own good. But in the main, it is a roundly entertaining, smartly constructed piece of filmmaking. The movie is at its cynical best when it holds a mirror up to television to reveal that, in the amoral climate of the 1990s, it’s becoming increasingly difficult to tell the heroes from the villains — if, indeed, there are any heroes left at all.