The Affair by Lee Child

This was such a prototypically "Jack Reacher" book in so many ways. First, it turns out to be the prequel of sorts to the first Reacher book published, The Killing Floor. It takes place in 1997, when Reacher is still an MP, before he leaves the Army.

He is sent to a small town in Mississippi, Carter Crossing, which is barely hanging on to existence due to the presence of a military base nearby which is used to train special forces troops. Someone, possibly from the base, has murdered a beautiful young woman in the town, and Reacher is sent go undercover (as much as a brute like him can) outside the fence to find out what the local sheriff knows.

He finds that the sheriff in town is not exactly what he expected - she's a former Marine Corps MP, named Deveraux. She's a little out of her depth in a murder investigation, but Reacher soon brings her up to speed, while trying to maintain the confidentiality he's been sworn to by his CO, Garber. The murder could turn out to be a political hot potato, as the commander on base is the son of Congressman Riley. Reacher soon learns that this is not the first murder with a similar MO, either, the killings started about nine months before his arrival in town.

The book contains the required faceoff between Reacher and some local thugs. As always, he puts them down quickly and efficiently, without doing too much permanent damage. There's a great conversation after the thugs gather four more of their friend to attack Jack in a dark alley. After Jack takes them all on and puts most of them in the hospital, he's talking to Chief Deveraux:

"'I gave them the chance to come back in numbers. And what did they do? They added two more guys. That's all. They showed up with a total of six. What is that about? It's deliberate disrespect.'
Deveraux said, 'I think most people would consider six against one to be fairly respectful.'
'But I warned them. I told them they'd need more. I was trying to be fair. But they wouldn't listen. It was like talking to the Pentagon.'"

I love Reacher.

One of the great things about this character is that he just does what he knows to be the right thing, without respect for what his orders are, whether it's strictly legal or not, or whether anyone agrees with him. He's like an unstoppable force of nature. Reacher readers are going to go absolutely nuts over this one.