Having run short on cash, Reacher has paused in his travels and is working in Chicago as a doorman when he stumbles into the kidnapping of FBI agent Holly Johnson. The pair are whisked across the United States in the back of a stolen Ford Econoline van, while back in Chicago Holly's colleagues frantically piece together the puzzle of her sudden disappearance.
Arriving in Yorke County, a (fictional) remote area of Montana, Reacher and Holly find themselves up against the Montana Militia, a band approximately 100 strong led by Beau Borken, a majestic yet ruthless megalomaniac intent on more than simple secession from the Union. Holly is the daughter of a US Army general officer - the Chairman of the Joint Chiefs of Staff. She's defensive about her family connections, having had to work hard to dispel notions of nepotism, so it's a while before she reveals to Reacher that she's also connected in a significant way with the President.
Further complications only add to the chaos and confusion already running rampant. The FBI has a mole named Jackson working under deep cover within the militia - but the militia itself has a mole infiltrated into the Chicago FBI teamgroup, who keeps Borken informed of every step taken against him.
There are also political complications, set out in several scenes at the White House, since Holly is the President's own beloved godchild. Much against his natural inclination, the President rejects the advice of Attorney General Ruth Rosen, who favors an all-out assault on the militia hideout. Instead, the President backs the hardnosed White House Chief of Staff Dexter, who is apprehensive of the political repercussions of a Waco-style bloodbath, which would make the militiamen into victims and martyrs. Therefore, Dexter - on behalf of the President - instructs the FBI and Army to go slow and avoid using their full force.
Adding even more to the confusion, the FBI believes that Reacher is the leader of the kidnap team. Major Reacher's old commanding officer, General Leon Garber, arrives to convince them otherwise - and eventually, takes a significant part himself in the rescue efforts. Of course, it is the redoubtable Reacher who has the main role - with some help from the kidnapped Holly Johnson, herself a formidable fighter who - unlike the classical Damsel in Distress - takes a prominent part in her own rescue. To the White House's relief, events in northwest Montana - amounting to small-scale war between the militia and Reacher's jury-rigged force of soldiers and FBI agents, involving dozens of casualties on both sides - remain unknown to the general American public. Efforts by militia survivors to get media attention are discredited due to their resorting to obvious exaggerations and conspiracy theories. This makes the book a kind of secret history.
As could have been expected, in the course of this adventure Reacher and Holly become deeply involved with each other. Still, Holly is in love with a fellow FBI agent - who also took part, at great personal risk, in saving her - and she still intends to marry him. Reacher gallantly, though heartbrokenly, says goodbye with a last passionate kiss, and sets off unencumbered on his wanderings, hitchhiking on an Idaho highway.