In the opening pages of The Song of the Cell (Scribner, Oct.), Siddhartha Mukherjee introduces readers to a medical miracle. Her name is Emily Whitehead, and she is famed for being the first pediatric patient to receive what is called CAR T-cell therapy, a treatment whereby by a cancer patient’s T cells are extracted from the body, modified in a lab to target the disease (in Whitehead’s case, acute lymphoblastic leukemia), and then infused back into the patient.

The success of Whitehead’s treatment was by no means assured: her prognosis was bleak, and the modified T cells initially went into overdrive, precipitating organ failure, “like a rioting crowd disgorging inflammatory pamphlets on a rampage,” as Mukherjee writes. It took an unlikely coincidence—one of her doctors happened to know of a new medicine that might tame the inflammation—and an 11th-hour pharmaceutical approval to turn around what might have been a tragedy. Now Whitehead is a bright symbol of the emerging field of cellular therapy. If she had died, Mukherjee writes, this groundbreaking form of treatment would have been set back a “decade or even longer.”

The Song of the Cell is replete with such narratives: high-stakes dramas that illustrate the thrill of scientific innovation, the centrality of the cell to human health and disease, the leaps forward in medical knowledge, and the perilous limits of that knowledge. If the book is a deep dive into the cell—its evolutionary history, how it works, how it can be harnessed to counteract pathology—it’s also a candid accounting of medicine’s knowns, unknowns, and unknown unknowns.

“Science is a human activity, and like all human activity it will have fissures in knowledge,” Mukherjee, 52, says via Zoom from his apartment in New York City. “I’m very interested, as a thinker, in these fissures.”

The book is the third in what Mukherjee refers to as a trilogy (though there may be, he says, a fourth). His first book, 2010’s The Emperor of All Maladies, drew on his work as a hematologist and oncologist to explore the history and even philosophical dimensions of cancer as well as the medical community’s efforts to comprehend and combat it. The book became a bestseller, won the Pulitzer Prize for nonfiction, and immediately lofted Mukherjee into the ranks of such authors as Elizabeth Kolbert, Oliver Sacks, and Andrew Solomon—the household names of science writing. In 2016 he followed with The Gene, which likewise became a bestseller. Both books have been adapted into documentaries by Ken Burns.

Like those books, The Song of the Cell is wide-ranging, taking readers from the discovery of the cell to the forefront of novel cellular therapies in development today. It’s peopled by a cast of scientific heroes (among them physician Frederick Banting and medical student Charles Best, who discovered insulin) and the occasional villain: Mukherjee tells the story of the Chinese biophysicist He Jiankui, who in the late 2010s ran afoul of the scientific community (and received a three-year prison sentence) when he violated medical protocols in a quest to be the first to edit the genes of a human embryo.

Mukherjee began writing the book four years ago, but the project acquired special urgency at the onset of Covid. “In some ways, the pandemic forced me to write,” he says. Though he continued to work—he is an assistant professor of medicine at Columbia University as well as a practicing physician and researcher—he found himself more homebound than usual. And Covid, a disease for which the understanding of cell behavior is crucial, gave the book a new frame.

“There was a powerful intersection,” Mukherjee says. “I hadn’t anticipated it.” The book, he hopes, will allow readers to step back and contextualize the great healthcare story of our time, to read about “not the crisis itself but what lies behind it”—i.e., cells.

Mukherjee, who was educated at Stanford, Oxford, and Harvard, is mindful of the challenges of writing about complex science for a general audience. He employs approachable metaphors that allow readers to visualize cell dynamics easily: a cell entering what’s called a “gap period,” he writes in the book, “is dipping its toes into the waters of cell division.” But he’s also not afraid to present his audience with language that smacks of MCAT test prep: in a discussion of autoimmunity, for example, readers learn what happens when the CTLA4 gene on activated T cells encounters its cognate binder B7.

“I don’t think there’s any part of the book where the science is compromised,” Mukherjee says. “But there are many parts of the book, of course, where the range of science has to be constrained. I can’t talk about exactly how the ion channels of the kidney regulate salt and water, but you can say enough about it that people get a general sense of understanding, and experts in the field also benefit.”

Mukherjee draws no major distinctions between his work as a physician and his work as a writer. “These professions: you can glide through them, and you don’t need to define yourself as one or the other,” he says. And he’s attentive, both in his dual career and in the book, to the ways language can be used as an adaptable medical instrument.

“It can be the way that a pathologist tells you this is what the diagnosis is,” Mukherjee says, “but it’s also, simultaneously, perhaps in the same day, the way that a patient tells you this is the form of my suffering.”

As a writer, Mukherjee also uses language to advocate for the medical enterprise while acknowledging its shortcomings—to navigate that tension using precise words. This is especially crucial for him at a time when, amid political hostilities arising from the pandemic, the scientific community often finds itself under attack.

“In the middle of the pandemic, people said, ‘The CDC got this wrong, the CDC got that wrong,’ ” Mukherjee says. “That’s because new facts were coming in. And when new facts came in, you couldn’t stick to the old ones. You had to change your mind. That constant updating has a humility attached to it, but more than humility it’s just the method we use.”

He adds, “Language can be used to distort science. That’s why I think you need really thoughtful science writers who can negotiate all that.”

Mukherjee says science writing at its best “dispels distortion and restores accuracy, but it does so in a way that’s not polemical—it’s about following the data, understanding the data, describing its limitations. All of this through storytelling.”

It’s through stories about figures like Whitehead that Mukherjee illuminates the adventure of science: its risks, its triumphs, its potential to unlock discoveries—figures who embody, as he writes in the book, “our desire to get to the luminous heart of the cell, to understand its endlessly captivating mysteries.”

Such stories bring the reader “into a world which you otherwise would not be able to inhabit,” Mukherjee says. “I find that very beautiful.”

Daniel Lefferts is a writer living in New York City.