After tangling with an extremist militia group in far northwestern Montana in his last outing, the third Jack Reacher novel finds the ex-MP digging swimming pools in Key West--about as far away from Northwestern Montana as one can get without leaving the United States. When a private investigator from New York named Costello shows up in Key West looking for him, Reacher has no idea who might have sent the guy looking for him or for what purpose, and so he tells Costello that he never heard of Jack Reacher.
Reacher is also working as security at a strip club and that same night two extremely unpleasant-looking guys come in looking for Jack Reacher. Again, Reacher denies knowing the guy. But then Costello, the P.I., turns up murdered with his fingertips cut off, and Reacher decides he'd better hightail it to New York to figure out what's going on here.
He quickly discovers that the client who hired Costello was none other than Reacher's old Army mentor and close friend, General Leon Garber. But Garber has just died and Reacher arrives as the funeral is underway. Garber's deliciously beautiful daughter, Jodie, tells Reacher that her father had been looking into the case of an MIA from the Vietnam War. The man, Victor Hobie, was piloting a helicopter that crashed in an inaccessible mountain region, and everyone on board was presumed dead, even though their remains were not recovered. For some reason, though, the military refuses to acknowledge Hobie as MIA, and they will not put his name on the memorial wall in Washington, D.C. Hobie's elderly parents are still grieving and Garber was attempting to resolve the mystery for them. Naturally, Reacher will take up the crusade.
Meanwhile, in New York City, a nasty corporate loan shark named "Hook" Hobie has gotten his hooks, literally and figuratively, into a desperate businessman named Chester Stone, who badly needs eleven million bucks on a short-term loan in order to save his company. Stone has no inkling that Hobie has every intention of stripping him of everything he possesses, right down to his boxer shorts.
Inevitably, of course, these two stories will intersect in a massive and very inventive climax. Along the way, there will be lots of action and violence and Reacher will have to be on top of his game all the way along. "Hook" Hobie is truly a deliciously nasty villain and, all in all, Tripwire is a lot of fun.