This is really an extended short story (novella? novelette? novelito?), and loony as all hell, and great fun. The earth, circa the Cuban Missile Crisis, is skinned "like a grape" and repositioned on a flat disk light years from our current galactic position and some many thousands of years in the future. If that bit of outlandish tomfoolery (carefully worked out for its physical implications, including the end of the space race) doesn't bring a smile to your face, skip this.
We open in this counterfactual 'seventies, amid a Cold War furor that is funhouse mirror to our own, even as its varied inhabitants scramble to make sense of this new world with old-world-order lenses. Carl Sagan and Yuri Gagarin have prominent roles, and there are sly allusions to Eugene Marais and Seth Brundle, but it'd be a shame to spoil the neat twists and ideas Stross packs into a breezy 90-odd pages. Like the best alternate histories, Missile Gap
provides some sly meditations on the nature of history (and the respective misconceptions of dialectic and anthropic notions thereof). My only complaint is that the assassination of JFK doesn't even get a wink.