It is the story of Mitchell Hundred, a fairly ordinary civil engineer who, one day in the late 90's, finds what is clearly a small alien device. The Box flares just once and then burns out, but not before affecting him forever by giving him the power to control machines with his mind. Being a good American, he decides that he should do what anyone does with super powers: go off and become a costumed hero, The Great Machine. He builds himself a jetpack, winds up with a couple of sidekicks, tries hard and does some good. The problem is, this is the real world: he's the only super-being in it (apparently), and being a super-hero doesn't actually work very well in practice.
At this point, things go off on a tangent from both ordinary reality and super-hero practice, as Hundred mounts a successful run for Mayor of New York City, and that's what the book is mainly about. The super-powers almost seem like a pointless distraction at times -- much of the story is simply about a good, politically centrist guy who doesn't fit into any of the usual pigeonholes, trying to do the right thing in a very important job. Major storylines revolve around him trying to deal with everything from garbage strikes to gay rights. His history as The Great Machine always lurks in the background, and there are frequent flashbacks to his heroic (and sometimes embarassing) exploits, but the story is mostly set during his term as Mayor, from 2002 to 2006. (Pretty much every scene has a specific date, and it's pretty well-synchronized with real history.)
But the super-powers still lurk in the background, and remember that this is *not* a superhero comic. That has a clear implication: it's a science fiction story instead. The great mystery of the book is where the Box came from, and why it affected him as it did. Threads of that are entwined throughout, and gradually lead up to the fairly creepy climax that occupies most of the last ten issues or so. Suffice it to say, every power has its price.
This story isn't as uplifting as Air, nor as mystical as Electric Ant, but it's a serious hardcore science fiction story in the best tradition -- mixing the real world with one or two specific fantastic premises, and seeing what comes out. Mitchell Hundred is *not* a typical saintly superhero: he's a decent, slightly bull-headed ordinary guy who is plunged into the grey world of politics. He is faced with compromises every day, sometimes comes to regret them and sometimes makes decisions that will shock the reader, but remains broadly sympathetic by generally trying to do the right thing as best he can figure it out.
A smart, interesting novel: recommended to anyone with a taste for both SF and politics, who finds the cut-and-thrust difficulties of public life interesting. It's a character study of a good man, but illustrates that, even for someone who tries to do right, politics is a lot more difficult than super-villains...