Guess Again — Charlie Donlea

Ten years after a teenage girl's disappearance, a bizarre confession breaks open the cold case in dangerous ways…and threatens to tear apart her small Wisconsin town all over again in the masterfully twisty new psychological suspense novel from the internationally bestselling author of Twenty Years Later.

For fans of Riley Sager, Anna Downes, Alex Finlay, Stacy Willingham, and Karin Slaughter.
  Ten years ago, 17-year-old high school volleyball star Callie Jones vanished from her quiet Wisconsin lake community. Her body was never found, and the case went cold, but the echoes of Callie's disappearance still linger. 

On the tenth anniversary, Ethan Hall -- a former renegade detective turned doctor -- is tapped to re-open the case. Ethan left law enforcement to escape his demons. But when his old partner makes a death-bed request to get the case off his conscience, Ethan reluctantly agrees to re-examine the evidence.

Word soon spreads and everyone in the small town of Cherryview feels a rush of hope that answers will finally be found. No one is more invested than Lindsay Larkin, Callie's high school best friend. Now a psychologist and the architect behind a wildly successful online counseling platform called The Anonymous Client, Lindsay has publicly and relentlessly pursued the truth about what happened to Callie.

Amid a sweltering heatwave, and just as Ethan's investigation gains momentum, a new client signs in to Lindsay's online portal and makes a devastating anonymous confession: “I killed Callie Jones, and I need your help to forgive myself.”

Lindsay's business and reputation depend upon keeping her clients' privacy, so she funnels scant clues to Ethan hoping he'll pick up the trail. But when Ethan's investigation leads to another missing woman, he realizes there's more to Callie's disappearance than anyone imagined, including ties to his own dark past that some are willing to kill for . . .