By Tally Daniels

The question at the center of Spare Parts is as old as humanity and as current as tomorrow’s headlines: What would you give to live forever, and who gets to decide? In David J. Glass’s provocative new Off-Broadway play, directed by Michael Herwitz, the pursuit of immortality becomes a high-stakes collision of science, wealth, and morality, where the promise of longer life reveals something far more unsettling about the people chasing it.

Photo Courtesy: Russ Rowland

That question lies at the heart of Spare Parts, a new Off-Broadway play by David J. Glass, now extended through April 30 at Theatre Row following strong reviews and audience demand. Directed by Michael Herwitz, the production is a sleek, unsettling meditation on immortality, scientific ethics, and the seductive pull of power.

Glass, a physician-scientist whose previous play Love + Science earned praise for its clinical precision, brings a rare authority to the material. Here, he imagines a world not far removed from our own, where a billionaire bankrolls radical aging research in pursuit of eternal life. The result is what one critic called a “brainy biotech thriller,” equal parts intellectual provocation and emotional reckoning.

Yet for Herwitz, the play’s appeal was not only in its ideas but in its people.

“I first encountered Spare Parts… at a private table read,” he said in a recent interview. “While I was tickled by the world of ultra-wealth… it was the relationships between the characters that most inspired me.” What he found was something unexpectedly intimate within the play’s high-concept frame. “Very quickly, I saw the story as two sets of Fathers and Sons… young men trying to do better than their fathers and perhaps in the process doing much worse.”

That generational lens shapes the production in subtle but profound ways. Though none of the four central characters are literally related, they are bound by mentorship, rivalry, and inheritance, of knowledge, of ambition, and of moral compromise. Each is, in some sense, negotiating how to surpass the figure who came before.

The cast, two-time Tony Award nominee Rob McClure, alongside Michael Genet, Jonny-James Kajoba, and Matt Walker, leans into those tensions with clarity and force. McClure, best known for his musical theater performances, reveals a darker edge here, while Genet brings gravitas and volatility to the mix. Kajoba and Walker, both steeped in classical and scientific training, respectively, round out a quartet that feels as intellectually credible as it is emotionally combustible.

Herwitz’s approach to directing the piece begins with language. “There are phrases that push, phrases that pull,” he said. “Language that says, ‘I love you,’ language that says, ‘fuck you.’” In rehearsal, he often strips down Glass’s scientific dialogue to its most basic impulses, encouraging actors to locate the emotional truth beneath the jargon. The effect is a production that feels immediate rather than abstract, driven less by theory than by need.

Photo Courtesy: Russ Rowland (Playwright David J Glass and director Michael Herwitz.  Cast and creative team on the first day of rehearsal for Spare Parts.)

That immediacy proves crucial in navigating the play’s tonal complexity. Critics have described Spare Parts as both “razor-sharp” and “darkly funny,” a balance Herwitz acknowledges was difficult to achieve. “There is no chance you can reach humor… without a high degree of consequence,” he said.

Rather than chasing laughs, the production allows humor to emerge organically from tension. In early previews, audiences helped map the play’s comic terrain. “We have no clue where the comedy… lies until there is an audience,” Herwitz noted. “It becomes a wonderful game of trial and error.” His guiding note to actors, “ask for the coffee, not for the laugh”, underscores a philosophy that privileges truth over performance.

Visually, Spare Parts occupies a world that feels both familiar and slightly off-kilter. The design team, including scenic designer Scott Penner, lighting designer Zack Lobel, costume designer Amanda Roberge, and sound designer Ryan Gamblin, draws on a range of references, from luxury retail spaces to the sleek menace of a James Bond villain’s lair. The result is an environment that suggests both aspiration and unease.

“I wanted the audience… to imagine these scenes playing out just a few stops up on the A train,” Herwitz said, “while also embracing that what they were watching was slightly adjacent to our reality.” The tonal benchmark, somewhat playfully, became prestige television. “We would listen to a sound cue and say, ‘Is this good HBO miniseries or bad HBO miniseries?’”

At the center of that world is a figure emblematic of a particular contemporary obsession: the billionaire who believes that with enough money, even death can be negotiated. In Spare Parts, that belief is not treated as fantasy but as a plausible extension of current trends, where private wealth increasingly shapes the direction of scientific inquiry.

For Herwitz, the theme is not abstract. “Today I plucked one of my first gray hairs,” he said. “I’d be lying if I said I didn’t feel a dose of dread.” And yet, working on the play has shifted his perspective. “I feel rather grateful that death can’t be solved,” he added, even as he acknowledges the allure of trying.

That tension, between acceptance and ambition, humility and hubris, animates the play’s central conflict. It is not simply a story about science gone too far, but about the human impulse to push beyond limits, regardless of cost.

Glass himself has noted that audiences seem eager to engage with those questions. “The extension gives us more time to explore this unsettling and fascinating world with them,” he said in a statement. “Theater is one of the few places where we can confront big scientific ideas and human consequences at the same time.”

If Spare Parts offers no easy answers, it does provide something perhaps more valuable: a sustained moment of confrontation. As Herwitz puts it, “I don’t care what the audience is thinking about as long as they are thinking about something.”

For 95 minutes on West 42nd Street, that seems more than enough.

Spare Parts runs through April 30, 2026, at Theatre Row (410 West 42nd Street). Tickets and additional information are available at www.sparepartsplay.com.