A tortured ex-Negotiator, once pride of the Boston Police Department is taken hostage in his home. A psychological confrontation takes place while the kidnappers demand that he completes a mysterious mission for them.

When her husband is hospitalized after a car accident, EMT Karen decides to rent out their spare rooms online. All goes well until Miranda moves in. Miranda quickly infiltrates all areas of Karen's life. When one of Karen's renters is found murdered, Karen becomes convinced Miranda was involved but has no idea that kicking her psychotic guest out will send Miranda into a murderous rage.