Something extraordinary happened this weekend at St. Mark’s Church. Heidi Latsky, the former Bill T. Jones dancer turned feisty downtown choreographer, premiered a dance so impassioned – and so good – that the packed audience sat spellbound. Performed in a hushed, intimate, dimly lit sanctuary, this was a forceful, urgent tribute to a lost mother.

Ms. Latsky’s mother, the program notes to “Disjointed” tell us, battled brain tumors for 35 years before her death a year ago. She had a “life-affirming sense of humor” and liked to wear hats, and “Disjointed” is set to the music she loved – good-time big band numbers, vigorous choral classics, and “The Umbrellas of Cherbourg.”The subject of the dance is her deterioration, as observed by an ethereal Greek chorus of 30, a gentle caretaker (Nathan Trice), and a shellshocked witness (Ms. Latsky).

It is characteristic of Ms. Latsky that she should give the role based on her mother to a man, Nathan Freeze, her longtime associate director. Ms. Latsky has always treated personal experience as a starting point, and she has said that what compelled her to make a dance about her mother’s death was the feeling it inspired of something epic – which is to say, something deep and shared. While conceiving “Disjointed,” she conducted workshops with other cancer patients, families, doctors, nurses, AIDS sufferers, and young prisoners at Rikers Island. She was making a dance not simply about her own grief – though “Disjointed” is filled with indelible images of that – but about people who struggle, and the people who have to watch them struggle.

In this she has succeeded astonish ingly. “Disjointed” begins when 30 white-clad figures of all shapes and sizes fan out across the shadowy sanctuary, surrounded by thousands of crumpled Kleenex. Each dancer stands in a fixed spot on the floor, performing a dance (Ms. Latsky’s 1993 solo “Grace”) in silent unison – elongating an arm, slowly raising a leg, running a palm along the chin, cupping a hand near the mouth. As they dance, there are sudden intakes of breath, abrupt shifts of weight.They gasp, as if some grief has knocked the wind out of them.

On the floor, front and center lies Ms. Latsky, all in black, absolutely still. As the chorus pauses another dancer in black, a man (Mr. Freeze) slowly raises one shaking, palsied arm. It is an unforgettable image: a quivering, diseased arm.And now Ms. Latsky stirs – a tiny body with a wild shock of dark hair, her arm tied to her neck by a long swath of brilliant red fabric. She dances angrily, insistently, until her mouth forms a scream. Then she unbinds her arm, dropping the fabric and turning abruptly away from it in the eerie half-light.

The duet that follows, surrounded by white angels, is remarkable for its blend of anger and tenderness. “The Umbrellas of Cherbourg” is playing, almost unbearably sweet, and the man’s arm shakes uncontrollably while the woman dances to him, looking haunted. He picks her up in a series of exhausted lifts, while those otherworldly white creatures look on, then slowly wander offstage.

The music changes to a chorale, and now the duet gets physical. The two combatants lock biceps and elbows, slapped together like two halves of the same grieving person.They butt chests and fling themselves into spins. Both are compact, tiny people, but they fill the space with lifts so unusual and potent that you wish they would linger so you could admire them.But they quick ly return to the fray, tugging on each other. They can’t get free.

The wrenching duet is followed by a Glenn Miller parade of chorus members, decked out in bright, fun hats, many of them belonging to Ms. Latsky’s mother. This breezy interlude begets a goofy, broad solo set for Mr. Freeze that is peppered with Ms. Latsky’s trademark vocabulary – powerful arms, stop-and-go sequences, lots of turns and one-foot balances. As Mr. Freeze takes a series bows, however, it’s clear he’s exhausted. He collapses, to be caught by the third and final black-clad dancer: Mr. Trice, playing a kind of beneficent caretaker.

But Mr. Freeze breaks free – he’s not ready to accept that. He goes to Ms. Latsky, the daughter and witness, and though they are entwined only loosely, they dance as if their lives depended on it. Slowly she steps away from him, instead dancing a formal, lush duet (guest-choreographed by Sean Curran) with the new figure, the caretaker.

Left alone in a corner, Mr. Freeze stands, his arm quivering, until the caregiver comes to carry him away. Mr. Trice carries him gently, but without touching him with his hands – he keeps his palms carefully outstretched. And as they step away, leaving Ms. Latsky finally alone, she throws her head back wildly and lunges deep, scampering sideways across the floor like a crab. Her body is at war with itself until the final moment, when her hands rise up as if to crush her skull – a stark contrast with the film playing behind her, which shows a younger, happier Ms. Latsky dancing while pregnant.

“Disjointed” is a work of tremendous power. While watching, I wished I could wave a wand and make Ms. Latsky the director of a well-funded, year-round company. Yet a dance like this is inseparable from her process. Those 30 angels, so attentive and loving, are old friends from all stages of Ms. Latsky’s dancing life; Mr. Freeze is a talented dancer of unorthodox body type who began his career as a muppet in “Sesame Street Live.”

With “Disjointed,” Ms. Latsky reminds us of the potential of downtown dance, and proves that a scrappy, intelligent choreographer and her talented, dedicated friends can occasionally produce astonishing and moving works of art.