Derek Charles (Idris Elba) and his wife Sharon (Beyonce Knowles) have a happy marriage and a young son, and everything seems to be going well for them. Derek just received a much sought-after promotion to Executive Vice President at his company, Gage Bendix, and Sharon is well on her way to graduating from business school. But a temp at Gage Bendix, a sultry blond named Lisa Sheridan (Ali Larter) threatens to tear Derek's family apart when she sets her sights on him. He rejects her every time, but she continues to become more obsessed with taking over Derek's family and life. Lisa's lies start to come between Sharon and Derek, and it's up to Sharon to stop Lisa before it's too late.