I am somewhat amazed that, despite having read all 10 main novels in the series, this is the first of Ben Aaronovitch's Rivers of London series that I've reviewed. It might seem odd that a book in a series with that title is set in and around Aberdeen, but you need to realise that the 'rivers' in question are genii loci - spirits of a river, one of whom is present. What I love about the series is that it combines police procedural (Aaronovitch delights in details like airwave radios and stab vests) with magic. In the early books, the central character, DS Peter Grant, is a newbie to the whole magic world, but ends up posted with a specialist unit dealing with magical threats (and trying to drag them into the twenty-first century). This time round, the oddities include dangerous magical beasts, kelpies and mermaids. This is, unfortunately, probably the weakest in the series. In part this is because Aaronovitch splits the first person narrative between Grant and his niec...