From the New York Times bestselling author of What Lies in the Woods, Yellowjackets meets Nine Perfect Strangers in a new novel of troubled girlhood, ritual, transformation—and murder.

Thirteen years ago, Nic, Alanna, Talia, and Jess were shipped off to Sanctuary Springs, a remote retreat among hills bubbling with hot springs. There, Dr. Elizabeth Sheffield—along with her enigmatic daughter Rachel—ran an experimental program for gifted but troubled girls. At the end of the program, she promised, these young women with their wasted potential would be completely reborn.

Three months later, the girls did emerge changed. They went on to be extremely successful. And none have ever revealed what really happened that summer in the hills.

When Nic is attacked and her fiancé killed, she retreats once more to Sanctuary Springs, where Talia has built a wellness retreat in the renovated facility, intending to bring a watered-down version of their "rebirth" to the masses. The group begins to flirt with old rites and rituals, but when Nic becomes convinced that her fiancé's murder is connected to what happened all those years ago, old tensions rise and long-buried secrets begin to resurface. As Nic confronts the truth of what happened that summer, she must decide whether to embrace the circle they created—or unravel it for good.