“Blessings,” Anna Quindlen’s fourth novel, starts with a familiar literary situation: A young couple abandons a newborn baby on a stranger’s doorstep.

But Quindlen adds unexpected twists and turns to this simple setup that bloom into a tender, honest story about what makes a person not only a parent, but a good parent.

The mysterious couple is drawn to Blessings, an old family estate, by its benedictionlike name, the small boat on its fishing pond and its green and gold awnings. They leave their infant daughter at the garage door where she is found not by the estate’s wealthy owner but by its caretaker, Skip Cuddy.

Skip, a good guy with a tough past who “just wished there’d been something permanent about his life,” gives up the free-spirited life of crime he shares with his friends from the local tavern to devote himself to the baby.

Throughout “Blessings,” Quindlen paints touching images of Skip taking care of the infant, which he immediately calls his own.

“A full day of work,” Quindlen writes, “most of it done with the baby on his chest, a wet spot of perspiration and drool always now faintly cool in the center of his sternum. Sometimes after she ate, she would sleep so deeply that he felt safe leaving her upstairs while he sprinted around, caulking windows, spraying the tomato plants.”

At first, Skip is able to hide the baby from his employer, Lydia Blessing, who at 80 was still locked in a time when people said “Pardon me?” instead of “What?” and all babies were expected to have a proper name and two parents.

Lydia, with one middle-aged daughter, Meredith, and no grandchildren, decides to help Skip keep the baby and keep it secret from the folks in town, where everyone’s personal business is, well, everyone’s personal business.

As the summer rolls on and Skip adjusts to fatherhood, Lydia becomes the grandmother she never was or thought she would be.

“It had occurred to Mrs. Blessing as she held the bottle while the child sucked noisily that perhaps she had never actually given Meredith a bottle,” Quindlen writes.

Lydia’s own story and deep secrets are slowly revealed as the novel progresses, her truths creeping out of the past, chapter by chapter. She has outlived the people she loved most her brother, her parents, her best friend and Quindlen brings them back to life with careful depictions that make the dead as vivid as the living.