Lyrical Media and Ryder Picture Company will adapt Sian Gilbert’s debut thriller “She Started It” for the screen. Jessica Sharzer, the screenwriter behind “A Simple Favor,” is set to direct from the script she co-wrote with Sarah Masson. Ryder Picture Company’s Aaron Ryder and Andrew Swett are producing with Lyrical Media’s Alexander Black. Lyrical is financing the development with Jon Rosenberg and Natalie Sellers executive producing. Casting is currently underway.

The announcement comes ahead of the June release of Gilbert’s second novel, “I Did Warn Her.”

“She Started It” follows Annabel, Esther, Tanya and Chloe, once inseparable childhood friends who have since drifted apart. Their adult lives haven’t unfolded quite as they’d imagined, but a shared past and buried secrets have kept them loosely connected. When they receive an invitation from former classmate Poppy Greer to an extravagant bachelorette weekend on a private island,...