Empire Games (Empire Games Series, 1) [Stross, Charles]

It's 2020. Two nuclear superpowers across timelines, one in the midst of a technological revolution and the other a hyper-police state, are set on a collision course. Each timeline's increasingly desperate paratime espionage agencies are fumbling around in the dark, trying to find a solution to the first-contact problem that doesn't result in a nuclear holocaust.

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And two paratime travellers, Ministry of Intertemporal Research and Intelligence Commissioner Miriam Burgeson and newly minted spy Rita Douglas--a mother and her long-lost, adopted daughter--are about to find themselves on opposite sides of the confrontation.