As shocking secrets are exposed, and a grand plan for the universe is revealed, River decides it's time she took control of events once and for all. Out in deep space, a clandestine society faces off with an ancient and powerful alien force – but, for River, there's an added complication. The Eighth Doctor has been caught in the middle, and she must make sure her future husband can arrive at his own destiny with all his memories - not to mention his lives - intact...