Sequel to "City of Pearl". Shan must now adapt to the changes the parasite/symbiont has made in her body, and help deal with the clashes between various races gathered around Cavanagh's Star.
The Doctor and Martha find themselves in 1909 in the Lake District of England. The Zygons have been hiding for centuries, but have now decided to take over the world.
I really liked this book. A 75-year old man enlists in the interstellar army. He's given a new young body, cloned from his old body, with bioengineered improvements. Mostly it's a story about how he adapts to this change in his life, but there is also a solid war/thriller plot.