In what the novel calls the "Age of Extinction," a grieving family of three travels to the edge of the world and stumbles into a scientific miracle. Jane, a graduate student in paleobiology (the study of prehistoric life through fossils), brings her two daughters, fifteen-year-old Eve and nearly thirteen-year-old Vera, to Siberia on a research expedition. Their father, Sal, a journalist who wrote about the iceman, a mummified early human discovered in the Italian Alps, died a year earlier in a car crash on a mountain road in Italy. The family is grieving, angry, and searching for a new beginning.
At a remote preserve on the East Siberian Sea, the group joins Dmitri, a Russian scientist restoring large grazing animals to the Arctic to regenerate grasslands and slow climate change. Jane's professor explains the CRISPR gene-editing process his lab uses to modify Asian elephant cells with mammoth traits, including fur, cold-adapted blood, and tusks, aiming to grow an embryo in an artificial womb. The professor and Todd, a postdoctoral researcher, treat Jane as a secretary rather than a colleague, and her children mark her as a domestic liability.
While exploring the cliffside beach, Eve and Vera dig a perfectly preserved baby woolly mammoth out of the frozen earth. They carry it back to camp, soaked and elated. The discovery gives Jane new standing, but when the men name the mammoth after Dmitri's family rather than the girls who found it, and tissue samples yield no intact cells, the familiar pattern reasserts itself: Credit flows away from Jane and her daughters. That night, the three lie on discarded bones by the sea, sharing vodka and food. Vera feels a rare, pure happiness.
Back in Berkeley, the professor assigns Jane's tusk-ring research idea to Todd, who later claims the hypothesis as his own at a gala. Furious, Jane retreats with her daughters into a rain forest exhibit at the museum, where she meets Helen, a wealthy Englishwoman who keeps exotic animals, including an elephant, on a fifty-acre preserve on Lake Como with her husband George, a retired veterinarian. When Vera jokingly suggests implanting Jane's mammoth embryos in Helen's elephant, Helen is intrigued. Her parting advice is that women should "care less, do more" (52).
Jane decides to act. She steals four modified embryos from the lab, packs them in dry ice, and flies to Italy with her daughters. At Helen's lakeside castle, George sedates the elephant and implants all four embryos. Jane is frightened rather than triumphant. Afterward, the family picnics in Helen's private museum beneath a reassembled mammoth skeleton. Though Jane had promised the girls a visit to the iceman exhibit in Bolzano, connected to Sal's research, she changes their tickets to fly home the next day.
What follows is the most ordinary stretch of the family's life. Jane works long hours in the lab, school resumes, and Vera turns fourteen. Against all probability, the elephant remains pregnant month after month. The family marks the second anniversary of Sal's death. News of a Chinese researcher placed under house arrest for gene editing alarms Jane, but she convinces herself the pregnancy will end on its own. A 6.3 earthquake shakes the Bay Area. Then Jane is assigned to spend the summer in Iceland studying human genetics.
In Iceland, Eve, now seventeen, falls in love with Lars, a twenty-three-year-old Icelandic man who lives in a hand-built seaside cottage. Vera trails behind the couple, lonely and envious. When Eve begins secretly spending nights at Lars's house, Vera tells Jane, who retrieves Eve and restricts her to daytime visits with Vera as chaperone. Eve is furious, accusing Jane of not understanding love.
Jane has obtained a scrotal sample from the iceman, hoping to compare ancient and Viking DNA and finish the article Sal was writing when he died. Eve, drunk and enraged, finds the specimen vial in the bathroom. In an act of rebellion, she draws the material into a needleless syringe and injects it into herself, then leaves the empty vial for Jane to find. Jane slaps Eve across the face for the first time. At that moment, Jane's phone lights up with a message from Helen: The elephant has given birth. Attached is a photo of a furry newborn animal.
The family rushes to Italy. The elephant mother rejected the baby and, during transport to a zoo, stepped on George's leg and broke it. In a pen beneath oak trees, the family finds Pearl: a three-foot-tall gray baby with a halo of red hair, a square forehead, and a single tiny tusk. Jane names her for the tusk.
Pearl refuses to eat. Jane sleeps in the dirt beside the animal, singing Sal's old lullabies to calm Pearl's wailing. While searching Eve's suitcase, Vera finds a positive pregnancy test. Eve does not know whether the father is Lars or, impossibly, the iceman. She resolves to terminate the pregnancy but is unsure how to manage it in Italy. Vera discovers a specimen tube of mammoth hair in the castle kitchen, suggesting someone is taking samples from Pearl. When Helen sends the girls out on her wooden boat, the vessel begins sinking. The girls are rescued, and Eve suspects Helen sabotaged the boat.
Helen throws a birthday party for George. During the celebration, Eve tells Jane she is pregnant. Jane surprises her with sympathy, sharing that she herself ended a pregnancy in college, and promises to help. Afterward, Helen privately tells Vera that George plans to sell Pearl to a dealer who supplies private zoos for the ultra-wealthy. She whispers that the keys are in the van, enabling the family's escape.
The next morning, Pearl is gone from her pen. Vera, who secretly moved the animal into the museum overnight, leads her family there. The mammoth is barely breathing, curled around the leg bone of the reassembled skeleton. They load Pearl into the van and drive away at dawn. Jane takes them to the place where Sal died: a granite wall on a steep mountain road. Vera presses her forehead to the stone and pockets a jagged rock. Jane yells to the mountainside that Sal is loved. The visit provides a measure of release.
Jane drives hours into a remote alpine meadow. When Pearl's feet touch wild grass, her posture brightens. She begins to graze eagerly. The food they never thought to offer is what she needed all along. Eve tells Jane the full truth about the iceman vial. Jane assures her the ancient material almost certainly contained nothing viable and that Lars is the father. She promises to help Eve end the pregnancy when they return to California.
Jane burns all her research notes about Pearl. She, Eve, and Vera take turns telling the story of evolution in the narrative style their father used in his classroom. Jane plans their return to ordinary life: writing a paper about the Siberian baby mammoth, which the professor has confirmed is the most recent specimen ever found, then getting a job and buying a house. Pearl, having eaten and rested, stands, shakes off leaves and sticks, and walks into the forest without looking back. The family watches her disappear. They knot their six hands together, holding a story no one else will ever know, and carry the secret of Pearl forward into their ongoing lives.