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.
After a few "mild" attempts on each other's lives, fueled by a mutual sense of betrayal, the marital spat culminates in a high-octane fight in the Smith house. After a long, evenly-matched fight, with their house shot to shambles, they wind up with guns in each other's faces. John balks, and lays his gun down; Jane finds she cannot shoot her spouse either, and both succumb to their love instead. Mr. and Mrs. Smith reunite and rediscover each other.