Wilfred Mott is very happy: his granddaughter, Donna, is back home, catching up with family and gossiping about her journeys, and he has just discovered a new star and had it named after him. He takes the Tenth Doctor with him to the naming ceremony. But the Doctor soon discovers something else new, and worryingly bright, in the heavens - something that is heading for Earth. It's an ancient force from the "Dark Times". And it is very, very angry. An adventure featuring the Tenth Doctor as played by David Tennant and his companion Donna.

五岁那年，斯加格拉断定：上帝并不存在。 面对如此启示，宇宙间的绝大多数人只可能有两种反应：如释重负，或是黯然神伤。只有斯加格拉不一样，他心想：等一下，这不就意味着有一个位置空出来了嘛。 许多年后的今天，斯加格拉低下头，第一次自信地打量这颗原始的星球。他最喜欢俯瞰众生。 考虑到种种因素，斯加格拉认为，在十分制里，地球只能打两分。这颗星球落后的让人沮丧，但事实上，也是完美的藏身之处，而他要找的那一位正是这么做的。他徒步走进这座名为“剑桥”的小城市，此行的目标，就在这个所谓的大学城里。 博士，博士…… 不知为何，这两个字使得斯加格拉暂时避退，重新盘算。他很确定在穿越半个宇宙的路上读到过“博士”的什么资料。克罗诺蒂斯教授的“非常老的朋友”不可能是地球人，因此博士必然是一名时间领主。 斯加格拉需要更多的情报。这位博士是谁？Doctor Who?