Poor Diana Cooke.

Born and bred to her purpose as surely as her majestic black steed Phaeton, she is barely out of Miss Porter’s when she is called back to her family estate, Saratoga, on Virginia’s Rappahannock River. Her father lost a leg in the Great War, and her mother can scarcely leave the house, so it is up to her, their only child, to marry into money and Save Our Home.

In “The Dying of the Light,” the new novel from Robert Goolrick (“A Reliable Wife,” “Heading Out to Wonderful”), breeding is overshadowed only by a family stronghold.

Although Diana and her mother scrounge enough cash to buy 12 gowns and 12 pairs of dancing shoes “from Montaldo’s, in Richmond” so she can attend 12 debuts, it is at her first cotillion, in Baltimore, where she meets the copper-haired Capt. Copperton.

These two have such an animalistic attraction it is a wonder they manage to wait until the week before the wedding to slake their ardor:

“He made love expertly, passionately, and he made allowances for her virginity, and was sweet and gentle with her, and the new world of womanhood opened like a lotus blossom.”

Too bad within a few weeks he will be tying her up, beating her and leaving her bruised and bloody for the maid to find.

If this prose sounds purple, wait for it: There will be domestic violence, death on horseback, repressed homosexuality, expressed homosexuality, dreadful poverty, adultery, theft, envy and, above all, enough details about interior decoration to make an Architectural Digest editor scream in ecstasy.

After an indeterminate number of years, during which the impoverished Diana has only loyal African-American husband-and-wife retainers Clarence and Priscilla to help her survive on the odd bit of country ham and the dregs of the liquor cabinet, fortunes turn.

The same night that a terrible storm nearly destroys Diana’s beloved library (a room never before mentioned), Diana’s son, Ash, is sent down from Yale for unspecified languor in his studies and brings along his tall, deliciously athletic former roommate. He also brings along access to his father’s bank accounts.

Before you can say “Save Saratoga!” Ash’s strange turban-wearing acquaintance Rose de Lisle materializes from Manhattan to redecorate, followed by an even stranger man named Lucius Walter, who will restore the very important library to its former glory.

No expense is to be spared, although suddenly Diana seems more concerned with her own architecture — “her full breasts, her tiny waist” — than with her all-important family home.

Everyone loves a good soap opera. But watching Goolrick’s real talent and compassion peep through the floor-length drapes of overwriting feels like seeing Dr. Oz behind his curtain.

Diana’s story, and the title’s metaphor, are real — by the mid-20th century, the Old South was greatly diminished. Goolrick’s depictions are based on the realities of one (formerly) grand family after another: eccentric relatives, a devotion to biscuits and gin, Sargent paintings in the hallway, perfectly ironed linen sheets on dilapidated beds.

The theatricality of the truth is more than enough without the added melodrama.

 Bethanne Patrick is the editor, most recently, of “The Books That Changed My Life: Reflections by 100 Authors, Actors, Musicians and Other Remarkable People.”

The Dying of the Light
By: Robert Goolrick.
Publisher: Harper, 288 pages, $26.99.