In reality, John and Jane are both skilled assassins working for different firms, both among the best in their field, but both with very different methods of assassination, with Jane working out thorough plans and John taking a less analytical approach. Each is concealing their true profession from their spouse. Under these cover stories, John and Jane balance their apparently mundane marriage which both of them find after a few years to be growing dull and suffocating with their secretive work. When both are assigned to kill Benjamin "The Tank" Danz (Adam Brody), they encounter each other on the job and botch the hit. Believing each had been sent to stop the other from completing their mission, they seek to discover and eliminate the other.