Ellie is horrified to learn that her husband Greg was killed in a terrible car accident. Even more awful, he was not alone and his female passenger was also killed. A tormented Ellie begins to question who the mystery woman was and whether Greg was having a secret affair. Drowning in grief, Ellie borrows her best friend's identity to infiltrate the mystery woman's workplace and leaves no rock unturned to find out the truth even if it puts her own life at risk.