Two identical baby girls are born to a Jewish family in Kishinev in 1880, on the same day their father is arrested by the czar’s secret police. Their mother, unable to earn enough on her own to feed all five of her children, takes the advice of the community and places the infants temporarily in Kishinev’s Jewish orphanage. Before she has found the means to reclaim them, though, one of the twins is spirited out of the orphanage by a childless Catholic couple from France.

Familial estrangement, the plight of the emigrant and Jewish identity are the themes of “What Disappears,” the fourth novel by author Barbara Quick, who lives in Cotati.

In the novel’s opening pages, the twins are reunited as 29-year-old identical strangers in the doorway of ballerina Anna Pavlova’s dressing room. Both women have landed in Paris with Sergei Diaghilev’s Ballets Russes, Sonya as a seamstress and Zaneta as an extra ballerina.

Her Jewish heritage having been kept secret from her, Zaneta has been raised to be reflexively antisemitic. Sonya, having lived her life believing that her twin died at birth, is overjoyed that Zaneta is, in fact, alive. When the two come face to face at the Ballet Russes, their reactions are as different as night and day. Sonya’s joy at finding her long-lost other half is in stark contrast to Jeanette’s horror when she realizes that her history is a lie.

What does it mean to be Jewish, Zaneta (who was renamed Jeannette by her French parents) asks her twin, who answers, “Our Jewishness is something like the connection between us, I think. It’s something the blood knows. Something deeper, older, and wiser than our own individual lives and all the selfish things we wish for.”

Quick grew up in the politically progressive incubator of the Mutual Housing Association of Crestwood Hills in Los Angeles. “Everything about my early childhood was culturally Jewish, but no one I knew was even the slightest bit observant,” Quick, 68, said in an interview. “I only started to ponder the question of my Jewishness when we moved for six years to the heart of John Birch country in Orange County in the 1960s, and I experienced antisemitism for the first time. Even though I knew next to nothing about Judaism, I defiantly wore a Star of David.”

Our Jewishness is something like the connection between us, I think. It’s something the blood knows.

Quick studied English and French at UC Santa Cruz, then worked as a writer at UC Berkeley and public information representative for the UC system. Jewish history became a subject of interest when Quick traveled to Italy to research her second novel, “Vivaldi’s Virgins.” That novel, which was published in 2007 and set in part in the Jewish ghetto of 18th-century Venice, is in development now as a miniseries by Lotus Pictures, Quick said.

She began writing “What Disappears” as a series of sketches based on stories told by her maternal grandmother, who grew up in a family of politically leftist, largely secular Jewish tailors in Kishinev. (Once part of the Pale of Settlement, the area of the Russian Empire where Jews were permitted to live, Kishinev is the capital of modern-day Moldova.)

“Nana’s memories of girlhood, ladled out in heavily accented English, always set my imagination on fire,” she said. “She spoke with unabashed nostalgia — even in front of my grandfather! — about the kiss she received, under a streetlamp in the snow, from Jascha, the pharmacist’s son, the boy she’d hoped to marry. Nana told me about a commission her mother won to tailor the hats and coats for the local parochial school that led the parish priest to shelter her family in the attic of the church during the pogroms against the Jews of Kishinev.”

Quick learned that her great-grandmother, a hard-working tailor whose primary clients were parochial school children, traveled by train to Paris from Russia by herself twice a year “to see the fashions.”

What could have been the incentive, Quick wondered, for these extraordinary solo journeys, which would have involved great risk, expense and no doubt social censure for a Jewish woman of modest means in the Pale of Settlement at the dawn of the 20th century?

“Nana took the answers to my questions to her grave, but they continued to haunt me,” Quick said.

Quick’s estrangement from her own younger sister, who stopped communicating with her a decade ago, provided the imaginative pathway for the plot of “What Disappears.” “We had had an extraordinarily close relationship, from the time of her birth, when I was 9 years old, until I left for college at the age of 17,” Quick said. “It was a great loss to lose contact.”

“What Disappears” also wrestles with the way that sisters can love and also hurt one another, how they compete and, also, either by luck or by wits, end up in wildly different life circumstances that can cause deep rifts — and what it means to suffer a loss from which it seems one can never recover.

“What Disappears” by Barbara Quick (Regal House Publishing, 312 pages). Quick will sign copies of the book Saturday, April 1, in the gift shop of the War Memorial Opera House in San Francisco, before and after the 2 p.m. performance of “Cinderella.”