Empire games / Charles Stross.

The year is 2020. It's seventeen years since the Revolution overthrew the last king of the New British Empire, and the newly reconstituted North American Commonwealth is developing rapidly, on course to defeat the French and bring democracy to a troubled world. But Miriam Burgeson, commissioner in charge of the shadowy Ministry of Intertemporal Research and Intelligence--the paratime espionage agency tasked with catalyzing the Commonwealth's great leap forward--has a problem. For years, she's warned everyone: "The Americans are coming." Now their drones arrive in the middle of a succession crisis--the leader of the American Commonwealth is dying and the vultures are circling. In another timeline, the U.S. has recruited Rita, Miriam's estranged daughter, to spy across timelines and bring down any remaining world-walkers who might threaten national security. But her handlers are keeping information from her. Two nuclear superpowers are set on a collision course. Two increasingly desperate paratime espionage agencies are fumbling around in the dark, trying to find a solution to the firs- contact problem that doesn't result in a nuclear holocaust. And two women--a mother and her long-lost, adopted daughter--are about to find themselves on opposite sides of the confrontation.