Bernard and Catherine are a happily married, professional, middle-aged couple. They are financially stable, have a group of supportive friends, and each feels secure in life. When Bernard misses his surprise birthday party because he is delayed in Frankfurt, his wife is disappointed but thinks no more of the incident. How could he know she had planned something so special? But when she listens to messages on his cellphone shortly afterward, she is shattered. Catherine becomes convinced he is having an affair behind her back and, quietly and methodically, she begins to plot her revenge.