River Song is on the trail of the mysterious, planet-killing SporeShips. Nobody knows where they come from. Nobody knows why they are here. All they do know is that wherever the SporeShips appear, whole civilisations are reduced to mulch. But River has help. Her companion is a handsome time-travelling stranger, someone with specialist knowledge of the oddities and dangers the universe has to offer. For Mr Song has a connection to River’s future, and he would never want his wife to face those perils alone…