John (Brad Pitt) and Jane Smith (Angelina Jolie), a couple in a stagnating marriage, live a deceptively mundane existence. However, each has been hiding a secret from the other: they are assassins working for adversarial agencies. When they are both assigned to kill the same target, Benjamin Danz (Adam Brody), the truth comes to the surface. Finally free from their cover stories, they discover that they have been assigned to kill each other, sparking a series of explosive attacks.
They lived in squares, they loved in triangles.