The First Doctor and his companions find themselves trapped within the city of Kiev, shortly before it is besieged by the Mongol Empire in 1240. As if that wasn't bad enough, the citizens of Kiev start suffering from a mysterious plague shortly after their saviour, a 'dark angel' that fell from the skies centuries earlier, is awakened. This is a thoroughly entertaining novel set during a period of history I knew very little about, so I ended up learning as I was reading - always an added bonus whilst reading. The majority of the story is written from the perspective of the Doctor's companion, Steven Taylor, which is another point in the novel's favour, as first-person narrative always goes down well with me. One thing that I found odd was that, although we're privy to Steven's thoughts, we don't actually find out anything about him. 'Who' fans will know that he's a space pilot from Earth's future, but he could just as well be a binman from the twentieth-century, his character is so lacking in this book. But that's a minor grumble at best. Fans of the Doctor's historical adventures should not be disappointed with this novel despite the rather jarring scenes with the eponymous alien 'bunker soldier' which the city's inhabitants view as their guardian angel against the Mongol hordes. A welcome addition to the 'Past Doctors Adventures' range.