A collection of short stories about the Doctor's time on the planet Trenzalore. Trenzalore was one of the more audacious conceits of the modern Doctor Who series. Featured in only one episode, The Time of the Doctor, it is implied that the Doctor spent 900 years defending the planet while waiting for his final death, having run out of regenerations. One consequence of this idea is that the Doctor spent about the same amount of time defending Trenzalore as he did Earth. The Doctor was supposedly about 1200 years old at the start of the episode, and he was 236 when he left Gallifrey, that means slightly less than 1000 years defending Earth. It also means that the entire body of Doctor Who adventures: TV, audios, novels, and comic books combined are roughly equal to the length of time he spent on Trenzalore.
Mountains of material could be written about the Doctor's time on Trenzalore, but if these stories are anything to go by it is probably not worth the effort. The stories are not bad, but given the constraints of the short format, the fact that we already know the start and the finish of the Doctor's time on Trenzalore, and the rather dull nature of Trenzalore itself, there is not a whole lot that the stories can accomplish. The stories feature four old enemies of the Doctor taken from the classic days of the series; the Ice Warriors from the 2nd Doctor's time, the Krynoid from the 4th Doctor, the Autons from the 3rd Doctor and subsequent appearances, and finally the Mara from the 5th Doctor. This is not a spoiler as all four are pictured on the book cover.
There are a lot of plot points from the episode that could have been expanded on or explained in this book but were not. Nothing about how the Silence changed from being invaders of Earth to being a religious order. Nothing about the crack in the universe that allowed Clara to contact the Time Lords, only a reference to Handles the Doctor's pet Cyberman head, not even a mention of Tasha Lem and her relationship with the Doctor. The whole thing feels kind of rushed, like they wanted to get something published before Trenzalore was forgotten. I hope in the future we will get more War Doctor material and not more Trenzalore.