Predator by Terri Blackstock
Krista’s sister, Ella, had disappeared from where she was riding her bike. Security camera captured her and then a van blocked the view. When the van moved, only the bike was there. A computer media called “Grape Vyne” was like Facebook. Because of all the information people put on this site is how predators were picking victims. After a grueling search and danger to Krista as well, but in the end, Ella had indeed been killed. Ryan who started the social network helped Krista pursue the killer. After several murders, the killer was found.