Twenty-three years ago, Maggie D'arcy's family received a call from the Dublin police. Her cousin Erin has been missing for several days. Maggie herself spent weeks in Ireland, trying to track Erin's movements, working beside the police. But it was to no avail: No trace of her was ever found. The experience inspired Maggie to become a cop. Now, back on Long Island, more than 20 years have passed. Maggie is a detective and a divorced mother of a teenager. When the Gardaí call to say that Erin's scarf has been found and another young woman has gone missing, Maggie returns to Ireland.

Dee has come to London to investigate the murder of a man he’d known during World War I when serving with the Chinese Labour Corps. No sooner has Dee interviewed the grieving widow than another dead body turns up. Then another. All stabbed to death with a butterfly sword. Will Dee and Lao be able to connect the threads of the murders—or are they next in line as victims?

Rough-around-the-edges Harriet Morrow has long been drawn to the idea of whizzing around the city on her bicycle as a professional detective, solving crimes for a living without having to take a husband. She seizes the chance when the prestigious Prescott Agency hires her as its first woman operative. The move sparks controversy—with skeptical male colleagues, a high-strung office secretary, and her boss, Mr. Theodore Prescott, all waiting for her to unravel under the pressure.

A hurricane is building, threatening the coastal town of Bois Sauvage, Mississippi, and Esch's father is growing concerned. A hard drinker, largely absent, he doesn't show concern for much else. Esch and her three brothers are stocking food, but there isn't much to save. Lately, Esch can't keep down what food she gets; she's 14 and pregnant. Her brother Skeetah is sneaking scraps for his prized pitbull's new litter, dying one by one in the dirt. Meanwhile, brothers Randall and Junior try to stake their claim in a family long on child's play and short on parenting.

In this prequel to the international best seller The Ruin, set 10 years prior, bright-eyed Carrie Ryan is at the very start of her career. When she has a hunch about an ongoing murder investigation, she knows it could be her only chance to prove herself and truly break into the “boys' club” of Dublin’s police force.