An insane man first loves then grows to hate his neighbor, an old man whose penetrating gaze unnerves the insane man. He plans a perfect crime and executes it one night. The next day, two officers knock on the insane man's door, investigating a shriek heard in the night. The insane man invites them in, answers their questions, and submits to an examination of his eyes by one of the officers, who proclaims him innocent. The insane man invites them to stay and relax awhile, then regales them with his theories of crime. His heart begins to beat louder. Angles on the set are skewed to suggest the man's internal disarray.
克里斯蒂安·沃尔夫（本·阿弗莱克 Ben Affleck 饰）具有破解复杂难题的天赋。当一位旧识惨遭谋杀，并留下一条“去找会计师”的神秘讯息后，沃尔夫不得不开始追查此案。当他发现得用更极端手段时，沃尔夫找了他久未连络、同时是名顶尖杀手的弟弟布莱斯顿（乔·博恩瑟 Jon Bernthal 饰）合作。兄弟俩与美国财政部副局长玛莉贝丝·麦迪纳（辛希亚·阿戴-罗宾森 Cynthia Addai-Robinson 饰）联手，一起揭露这桩致命阴谋，却让他们成为冷血杀手集团的目标，这群杀手无所不用其极也要掩盖秘密。
