When David (Liam Neeson) misses his flight home from New York and, as a result, the surprise party his wife Catherine (Julianne Moore) has planned for him, Catherine is forced to swallow her disappointment and any suspicions and return to the waiting guests. Reading a text message sent to David’s phone the following morning from one of his female students, Catherine's fear grows. The successful couple, Catherine, a doctor, and David a professor of music, have a 17-year-old-son, Michael (Max Thieriot), and to an outsider, they have everything. But their careers and raising a child have put strains on the marriage; their relationships is suffering greatly from loss of communication and intimacy.