At the start of the film in an opening sequence the tech man helplessly witnesses the brutal rape & killing of his wife & the killing of his daughter. He is frustrated beyond belief when he realizes the man will go scott free. The prosecutor tells him, ruefully, "It's not what you know that will convict them, it's what you can prove in court." And according to court procedure, the killer is set free on procedural legal basis.
The avenging man's rage takes ten years to reach action; he insists he is out for justice, not revenge, then proceeds methodically to carry out his incredibly clever, deadly vigilante work.
Movie making is the art of making the improbable seem possible, and director F. Gary Gray directs a well crafted film with taut suspense in mind, making the incredible action believable by doling out just enough material to tell us what is happening without giving away how it is happening - until the very end. He is assisted by Jonathan Sella's perceptive camera work, mixing in location shots of the city of brotherly love with carefully controlled lighting & angles for the best intimate, dramatic effect. Brian Tyler's score, as well, supplies appropriate moods without hitting us with ear-shattering intensity. The cast is uniformly believable, with Jamie Foxx, perhaps a trifle too continuously restrained.