Lanier is inspired by the true events of Oscarville, Georgia, and the story of a detective who’s forced to come to a realization of the dark truths hidden at the bottom of Lake Lanier. Jeff Stevenson, his wife, and his daughter head off to a fun weekend getaway at Lake Lanier to celebrate his daughter’s birthday. The vacation turns into a workcation for Jeff to solve a drowning case when he decides to go undercover to work with a local detective named Daniel Wilson. As they work together, Jeff denies Daniel's theories that Lake Lanier is haunted, not to mention the history of the fallen city under the lake, Oscarville. A once thriving black community that was destroyed due to allegations of the rape and murder of Mae Crowe in 1912. Jeff's denial leads him to become increasingly concerned through a series of events. His worst fears soon become a reality when three masked strangers force themselves inside the home, forcing himself and his family into a fight for survival.