Marian Taylor, the central figure in Mary Gordon’s new novel, “There Your Heart Lies,” rejects her Catholic faith. She enters into a sham marriage with a doctor who had been the lover of her gay brother, who committed suicide in New York after being demonized by her father. Marian poses as the doctor’s nurse, and they run off with a boatload of anarchists and communists to support the cause of government loyalists fighting the Fascist, Catholic-backed rebels in the 1930s Spanish Civil War.

(Pantheon)

Decades later, Marian’s granddaughter, Amelia, travels to Spain to find answers about her beloved Meme’s adventures. From there the book toggles between Spain around the civil war and Avondale, R.I., where Marian is dying in 2009.

Gordon frequently writes about Catholic themes, and in “There Your Heart Lies,” her characters are unstinting in their indictment of the church for its ardent support of the Fascist leader Francisco Franco, who would head a military dictatorship in Spain for more than three decades until his death in 1975.

“The war was so much about the Church,” Marian says. “The Church that was hated because it had always been on the side of the rich, so that the burning of the churches, the killing of priests, was justified, was celebrated.”

Marian becomes disillusioned as the lopsided conflict tilts inexorably in favor of Franco’s forces, who benefit from the firepower given them by Germany’s Adolf Hitler and Italy’s Benito Mussolini. She tires of the squabbling among the foreign volunteers, who include hundreds of Americans known as the Abraham Lincoln Brigade.

Separated from her fake husband, she marries a local surgeon and gives birth to their son. She’s taken in by her husband’s staunchly Catholic family in the seaside town of Altea. Marian’s domineering mother-in-law, a pharmacist, surreptitiously drugs her, regularly feeding her a phenobarbital-spiked tonic that leaves her in a woozy stupor for years. The mother-in-law also inculcates Marian’s son in a twisted, obsessive brand of Catholicism and turns the boy against his mother.

“She worships the Church, not God, and she worships fascism,” says a priest who attempts to explain the mother-in-law’s cruelty to Marian. “She worships your child as if he were not a child of God, but a little jeweled god himself.” For all her duplicity, the priest says, the mother-in-law may have been motivated out of concern that Marian would be labeled a communist by Franco’s fearsome national police force, the Guardia Civil, and that the boy would be taken away to an orphanage for “the children of people they calls ‘reds.’ ”

Author Mary Gordon (Christopher Greenleaf)

Isolated much of the time, Marian longs to “rip the pictures from the walls: the bleeding Christs, the bleeding saints, the bleeding bulls.” She looks at an image of “The Sacred Heart, blood shooting out in diagonal needles from what seems like a pimento in the center of the Savior’s chest.” She remembers her husband telling her “about the Spanish love of blood.”

Sadly, this sort of hackneyed and debatable oversimplification of Spanish tastes and manners runs throughout this book, which betrays little of the graceful writing Gordon has displayed during her long, distinguished career. At various times, characters comment about “that Spanish insistence on everything being black and white” and the “Spanish walk, marked by its verticality.” A physician tells Marian that in Spain, “to be fanatical is not unusual” and awkwardly observes that “this is Spain, country of easily taken offense.”

Even something as simple as a description of horchata, a popular Spanish refreshment, misses the mark. Gordon describes it as “the iced almond drink that is a Valencian speciality.” As any mildly inquisitive tourist knows, in Valencia horchata is made from chufas, a tuber, and their provenance is so zealously guarded that a regulatory board oversees the geographical region where they’re grown.

The plot has all the makings of a fine tale, but the book’s narrator has the tiresome, pedantic habit of stating the obvious. “The swans represent the whole of her past to her,” the narrator says about one character. And Gordon leans far too often on tired, watery metaphors. Marian’s love for her father “had run through her life like a stream.” She wishes she’d closed the “sluiceway” on the “current” of her memories. Her thoughts are “minnows in a stream,” her mind “a dirty frozen pool.”

What happens, to borrow from Gordon’s linguistic playbook, is that a good story gets hopelessly drowned.

Manuel Roig-Franzia is a writer for The Washington Post.

There Your Heart Lies

By Mary Gordon

Pantheon. 320 pp. $26.95