Jack (no last name) is a repairman by trade. He doesn't fix appliances; he fixes problems. If you're having trouble, and you need help that the cops can't provide, Repairman Jack can help you, for a fee (cash, please). Need somebody found? A cult disrupted? A blackmailer dissuaded? Jack can do it, the soft way or the hard way.
His business works on word of mouth. Jack doesn't advertise. He also doesn't vote, have a driver's license, pay taxes, or follow New York City's strict firearms laws. He doesn't own stock, or real estate; his investments are in numismatics and bullion. Jack has an unusual lifestyle: he wants to be invisible. This creates strain on his relationship with his love Gia, who once left him briefly when she found out about what he did for a living. And Jack is devoted to Gia, and her daughter Vicki. He wants to be a family man -- but a family man has to exist, on paper. That poses problems for Jack.
Also posing problems: the looming threat of The Otherness, a great evil from outside the universe. There's a great war going on, and the Earth is a tiny part of it, like one of those worthless islands the US and Japanese slaughtered each other over in the Pacific. Unlike every other great war in fantasy, it's not a war between good and evil. It's a war between the evil of the Otherness and the currently-reigning complete indifference. Jack finds himself being drafted to help out the devil we know, in his own way, by taking cases that deal with various aspects of the Otherness's invasions. He's mainly a solo act, with supporting turns by Gia, Vicki, and Abe, a portly, Yiddish-spouting sporting goods store owner who goes out of his way to chase customers off because the store is merely a front for his real business: selling guns without all that pesky government oversight.
It's a great horror/action series, with little tastes of libertarianism here and there, as Jack tries to live as a free man in a world increasingly determined to number-stamp everyone and everything. (Which makes me think he and Dean would get along really well.) I feel obliged to mention there's not much slash potential, as Jack is not only devoted to Gia and Vicki but doesn't have a close relationship with many other men but Abe. For those with squicks, I should note that author F. Paul Wilson also ruthlessly kills even the most sympathetic guest characters, often in truly horrible ways. The series is a little heavy on women in refrigerators, but they're not alone because Wilson happily chucks men in fridges right along with 'em. By which I mean: PEOPLE DIE LEFT AND RIGHT, especially if you like 'em. Usually, not long after you start to really like and respect them. So the series can be a downer, but it is also twelve kinds of awesome. THE TOMB is the first novel, but you can dive in pretty much anywhere. Repairman Jack, folks. Check him out.