A Wall Street Journal bestselling series.

Searching for a missing diver takes a Florida detective on a deep-diving adventure in a gripping thriller by the Amazon Charts bestselling author of Sea Castle.

After the Underwater Investigation Unit’s disbandment, public outcry ushers Sloan McPherson and her partner, former navy diver Scott Hughes, back into the depths of crime solving. But Sloan’s return comes with a personal case.

Longtime family friend Fred Stafford has disappeared. Left behind: his abandoned truck in the vicinity of an unmarked sinkhole and new findings that have Sloan second-guessing everything she thought she knew about the man. There are his gambling debts, his association with a treasure-hunting band of underwater cavern junkies called the Dive Rats, and most alarming of all, a discovery in Stafford’s storage shed that raises the stakes even higher and plunges Sloan into an unfathomable mystery.

As Sloan’s investigation unfolds, a tragic Florida cold case, local superstitions, and a shocking conspiracy collide. For Sloan, finding Stafford and uncovering the buried secrets of the past soon drag her deeper into the dark unknown than she feared.

Andrew Mayne is the Amazon Charts and Wall Street Journal bestselling author of The Girl Beneath the Sea, Black Coral, Sea Storm, Sea Castle, and Dark Dive in his Underwater Investigation Unit series; The Final Equinox and Mastermind in the Theo Cray and Jessica Blackwood series; The Naturalist, Looking Glass, Murder Theory, and Dark Pattern in the Theo Cray series; and Angel Killer, Name of the Devil, and the Edgar Award–nominated Black Fall in his Jessica Blackwood series. He was the star of A&E’s Don’t Trust Andrew Mayne and swam with great white sharks using an underwater stealth suit he designed for the Shark Week special Andrew Mayne: Ghost Diver. He currently works on creative applications for artificial intelligence and as the science communicator for OpenAI. For more information, visit www.andrewmayne.com.