Iron Sunrise — Charles Stross

A G2 star doesn't just explode--not without outside interference. So the survivors of the planet Moscow, which was annihilated in just such an event, have launched a counterattack against the most likely culprit: the neighboring system of New Dresden.

But New Dresden wasn't responsible, and as re deadly missiles approach their target, Rachel Mansour, agent for the interests of Old Earth, is ,signed to find out who was. Opposing her is unknown--and unimaginable--enemy. At stake is not only the fate of New Dresden but so the very order of the universe.

And the one person who knows the identity or rat enemy is a disaffected teenager who calls herself Wednesday Shadowmist. But Wednesday has no idea what she knows..