Jack Reacher is an adaptation of Lee Child's 2005 novelOne Shot.A man with a sniper rifle goes to a parking garage overlooking the Allegheny River in Pittsburgh, and kills five people across the river in the park, seemingly at random. The police are quick to find evidence and the man, James Barr. When they have him in for questioning, he writes "GET JACK REACHER" on a notepad. Before they can contact Reacher, the man is brutally beaten by fellow inmates.Reacher arrives and begins to examine the case, discovering the case is not as cut-and-dry as it seems...
Tropes in Jack Reacher:
Affably Evil: The Zec's only motivation is not starving to death. As a Russian refugee in his late 60's with three fingers left, crime was the only way he could find to pay his bills.
All Girls Want Bad Boys: When Jack asks Sandy why an intelligent, attractive, and nice teenage girl like her would put up with losers like Jeb Oliver and his crew, she says: "It's what girls like me do." She even hits on Jack again, because she believes he's a bad boy or at least a strong man.
Fingore: Zec had to bite off some his fingers during his imprisonment in Siberia. He tests fortitude of one his hired men by forcing him to try to do the same.
Foreshadowing: When the movie actually takes a break from the investigation of James Barr to show video of each person who ended up shot going about their business leading up to being shot in the park, you know one of them will actually be important to the plot or they would simply be mentioned in an offhand manner.
Enemy Mine: Barr is invoking a form of this when he asks Emerson and Rodin to find Jack Reacher. Reacher despises Barr for his crime in Baghdad that he got away with and even promised to bring him down if he ever slipped up again. But Barr also knows Reacher's the only man who can see through the evidence and determine that Barr wasn't the shooter and figure out who framed him.
Good Is Not Nice: Reacher can come across as a real asshole, often insulting and bullying people even if it's for a good cause.
Grievous Harm with a Body: Downplayed; in the bathroom fight scene, Reacher knocks down one guy onto another and smashes the top guy's head into the bottom guy's until both are out.
Hostage Situation: Defied by Reacher. Though he's going to rescue the girl, he refuses to do it by their rules, and warns that a man like him will be no end of trouble if so inclined. He instead forces them to give up their location, then attacks on his schedule.
Oh Crap: The look on the Zec's face when the man who would do anything to survive realises he's just talked himself into a death sentence.
Orgy of Evidence: This is what the case against James Barr becomes. However, what makes Reacher suspicious is not the amount of evidence, but that the investigative team thought to look for a clue that they had no reason to believe existed.
Pittsburgh: A lot of footage of The Allegheny River across from PNC Park and the Fort Duquesne Bridge. (If you look at the picture of the city on the page for Pittsburgh, it's the section directly behind the first bridge over the river to your left. Gives you an idea of how far he was shooting, too.)
Sociopathic Soldier: Jack lists four different types of soldiers that he knew from experience — Military Brats who followed their parents into the military, patriots, people looking for work, and people who join so that they can kill without repercussions. James Barr was this type, having eventually snapped and gone on a shooting rampage in Baghdad just so that he could feed his urge to kill; the only reason he got away with it was because, unbeknownst to him, his victimsall had it coming, and the PMC that they worked for didn't pursue justice because they knew that the victims' crimes would be exposed if they did so.
Reacher fully believes that Barr is the shooter and is there only to make sure he goes down...until he sees the quarter with Barr's fingerprint on it with the evidence. Not only does it make no sense for Barr to make sure he's paid the parking meter right before shooting five random people in cold blood, but it also makes no sense for Emerson to investigate the meter unless he knew the quarter would be there beforehand.
Next, with a seed of doubt in his mind, Reacher investigates the location of the shooting and deems it a poor vantage point due to the location of the sun and targets moving left-and-right. He finds another location nearby that would have been ideal for a shooter and would have prevented empty shells from being left behind as evidence. He also discovers that Barr was deemed a merely 'decent' sniper while in the Army and wasn't good enough to shoot so accurately from a non-ideal location.
All six shots that the sniper fired came in quick succession...except for a several second pause between shot one and two. Reacher determines that this means the sniper was extra careful with his second shot, meaning the second target was killed for an actual purpose.
Five of the shots the sniper took were perfect, while the fourth shot missed by a lot and ended up in a location where the bullet would be preserved perfectly to be used for evidence. Reacher reasons that the shooter intentionally put one of his rounds in a perfect location to be found by police for the evidence in the case against Barr.
Reacher uses a fake name when Sandy approaches him at a bar, and sees she's thrown by it even though she had no reason to be. From this, and the barfight that follows, he believes that someone is trying to run him off the case, which leads to him eventually blowing the entire plan.
Jeb hasn't been seen for awhile by his friends, who all think he's left town. Reacher checks his house and finds evidence that Jeb quickly packed some things and left...except the shower curtain is gone too, leading him to think that someone (who wasn't very smart) simply raided the house to make it look like Jeb had left.