The Lie Between Us by Amanda McKinney

This detective’s secret will follow her to the grave…

At three in the morning, Detective Ame Bassette receives a panicked call from her sister Delphine who has just killed her drug-dealing boyfriend. Ame makes a snap decision—to risk everything to save her sister from spending life behind bars. Together, they go on the run but quickly discover that some secrets will follow wherever you go.
After hours of driving, Ame finds herself lost in the dangerous swamplands of south Louisiana, where she comes across Gramarye Lodge, a run-down hotel with a sordid past—that may be connected to a horrifying cold case Ame once investigated.
Soon after checking in, it becomes apparent that someone doesn’t want Ame to leave. Between the eccentric lodge owner, the mysterious guest on the third floor, the wayward teen, and Ame’s mentally unstable sister, Ame begins to question who she can trust… and if it isn’t only her sister’s secrets that are coming to light.