I didn't have any particular hopes for this comic, but it turns out to be quite good. The authors do a great job of capturing the feel of the Rivers of London novels and translating them to the comic field. We get a great sense of "real" police work, a spooky supernatural mystery (that's really quite wonderful), and nice characterization of Peter. 
 I think that Nightingale is perhaps a bit too active and everyone is perhaps a bit too eager to show off their magic, but other than those nitpicks, this is a fine short story addition to the Rivers of London mythos (and more like 4.5 stars than 4).