In the opening moments of "Frozen," Bryony Lavery's scalding portrait of a murderer of young girls, a researcher skillfully played by Laila Robins opens a handbag and screams into it until her face turns scarlet. A terror of some sort has overwhelmed her, but as we are to discover in this gripping drama, it isn't so much the nature of the crimes she analyzes as her inability to deter them that seems to trigger the outburst.

An infuriating lack of breakthrough in the face of death bedevils the medical expert in another play receiving a strong production here: a revival of Larry Kramer's blistering 1985 AIDS drama, "The Normal Heart." Facing a panel of obstructionists from the National Institutes of Health, who refuse her pleas to finance early studies into the disease, an irate doctor (Joanna Gleason) takes the piles of documents she's brought to the hearing room and throws them at her examiners.

So much loss, so much pain, so little understanding. What both plays put a human face on so effectively is the fallibility of science, how what we know has nothing on what we endure. Though they were written two decades apart -- Lavery's play is new -- and their subjects are entirely distinct, each work in its way addresses the anguishing frustration of a world that has the tools to prevent suffering but none of the proper instruction manuals.

Despite the agonies it chronicles, "Frozen" is occasion for a toast: It's a tautly wound, elegantly acted, deeply thoughtful drama, a category of theater Broadway almost never finds room for anymore. Three resourceful actors -- Robins, Swoosie Kurtz and Bryan F. O'Byrne -- offer the requisite perspectives on this story of the aftershocks of child murder. Kurtz portrays the working-class English mother of the slain girl; O'Byrne plays the serial killer who suffocated her; and Robins is the American psychologist who has come to an English penitentiary to study him.

You may think you've seen or read this story a hundred times, but the performances mesh with such finely wrought authenticity, the direction by Doug Hughes is handled with such affinity for illuminating detail, that "Frozen" fills you with the sensation of new discovery. As its title suggests, the play identifies something of the coldness of the heart that each character experiences: the bloodless fury of the killer; the icy veil of grief maintained by the mother; the emotional isolation of the psychologist.

While the audience inevitably sympathizes with Nancy, the mother, neither Lavery nor Kurtz guides us comfortably to that position. Cleverly, the dramatist leaves open the possibility that the play's sad, albeit just, conclusion has been engineered by Nancy, that she's far more manipulative than we've been led to believe.

Kurtz is a marvel of control and moral certainty as Nancy, whose 20-odd-year vigil for her dead daughter prompts her to seek a visit with the killer. The result is a scene across a prison table -- Hugh Landwehr's Spartan set matches the play for shimmering simplicity -- that brutally captures the torment of both the victim's family and the victimizer. O'Byrne backed out of the Kennedy Center's "A Streetcar Named Desire," in which he was to have played Mitch, so that he could remain with "Frozen" at the Circle in the Square. It's easy to see why he felt he had to: His performance as a profoundly damaged, tattoo-covered psychopath is as scary and disturbing as anything you'll encounter on Broadway these days.

If the emotional scars exposed in "Frozen" have a timeless quality, the concern with bringing back Kramer's play was that it might feel dated. It turns out, however, that the reappearance of "The Normal Heart" -- a full-throttle raging at the injustices of the early efforts to fight AIDS -- is totally justified. It deserved another staging for many good reasons -- and for no more crucial one than that Kramer was right to have shouted as loudly as he did.

The cast of the Worth Street Theater production, directed by David Esbjornson at off-Broadway's Public Theater, isn't as uniformly impressive as that of "Frozen." But Raul Esparza, a standout in the Kennedy Center's Sondheim Celebration two years ago, here gives strength and emotional heft to the pivotal role of Ned Weeks, an insufferable rabble-rouser, based on Kramer himself, who embodies the play's white-hot fury.

"The Normal Heart" may be intemperate at times, but at others it remains a shattering snapshot of the early, terrifying years of the crisis. No scene captures the scope of the sadness more completely than one in which Mickey (Fred Berman), who's working the phones of an AIDS hotline, has a breakdown under the weight of all the collective despair. Like Kurtz in "Frozen," Berman is superb at evoking the tragic burden of those who have to go on living.

Frozen, by Bryony Lavery. Directed by Doug Hughes. Costumes, Catherine Zuber; lighting, Clifton Taylor; original music and sound, David van Tieghem; makeup and tattoo design, Angelina Avallone. With Sam Kitchin. Approximately 2 hours 10 minutes. At Circle in the Square, 50th Street west of Broadway, New York. Call 800-432-7250 or visit www.telecharge.com.

The Normal Heart, by Larry Kramer. Directed by David Esbjornson. Set, Eugene Lee; costumes, Jess Goldstein; lighting, Ken Billington; sound, Tony Meola. With Paul Whitthorne, Jay Russell, Billy Warlock, Richard Bekins, McCaleb Burnett. Approximately 2 hours 50 minutes. Through August at Public Theater, 425 Lafayette St., New York. Call 212-239-6200 or visit www.telecharge.com.

Swoosie Kurtz plays the mother of a murdered child in the tautly wound, elegantly acted "Frozen."McCaleb Burnett, left, and Raul Esparza face off (with Billy Warlock in the background) in the revival of the 1985 AIDS drama "The Normal Heart."