This is surely one of the best New Series Adventures, and one of the better Who novels in general. It is largely set in Bromley, which may not sound like a promising start, but this becomes the jumping off point for the Doctor (Nine, in this case) and Rose to get involved with Bromley's prehistory, where Neanderthals, local homo sapiens, and humans who have travelled there from the far future are all under threat from ambitious monsters and montrous ambition. Meanwhile, in the early 21st century, Jack Harkness is helping a displaced Neanderthal settle into contemporary Bromley. There is a certain amount of playing the situation for laughs, but also a bit of exploration of what it is that makes us human. The question of whether or not this applies to the Doctor lurks in the background, of course, but it's more about Rose and the people she meets, with the Jack story line operating as a contrast. Very interesting, and recommended.