A detective (possibly in Florida) meets a woman in a bar. She tells the detective she is considering killing her abusive husband. She drives to (Atlanta?) then rents a car to return home, but finds her husband dead of a gunshot. She convinces the detective to help her cover up the murder, since she would be suspected. They remove the body and he cleans up the room, even filling in a bullet hole in the wall. They dump the body in a (lake?). The detective’s partner, though, sees through the cover-up and keeps steering cops towards the detective. Cops find the body and find that he was shot with the detective’s gun. The detective finally realizes that his partner had set up the original meeting and switched his gun while he was talking to the woman. He tries to capture or kill his partner, but the cops kill him as he tries to retrieve his gun from his partner’s car. The woman then realizes what she has done and kills his partner. I believe the title had something to do with the body of water where they hid the husband’s body.

Question is closed for new answers.
Selected answer as best