A novella set in the period between Foxglove Summer and The Hanging Tree which sees Peter Grant and Jaget Kumar of the British Transport Police (one of the regularly recurring characters in the series) trying to sort out a ghost on the underground. As a novella, there’s not as much time for the ongoing story ark, so this doesn’t delve into the defection of Lesley May, but it does bring in Peter’s teenage proto-wizard cousin and a nascent river god who has been adopted by a well-meaning childless couple. An excellent stopgap while we’re waiting for the next full length book. It’s got all the trademark elements of the series and Peter’s wry and funny ‘voice’.