“Lies Sleeping,” by Ben Aaronovitch, is Book 7 in the “Rivers of London” series. I found it both delightful, and, for the most part, quite coherent. The POV character is Peter Grant, although it took me quite a fre pages before I harvested that bit of info from the book. He is a member of a London-based police unit, which works exclusively on cases in which criminals use magic to commit their crimes. He himself has magic powers, although some members of his unit do not, and a few others are more powerful.The current target of their investigations is one Martin Chorley, a bad, wicked, and proficient wielder of magic they have associated with a number of prior crimes. He appears to be using former members of an Oxford College club called the “Little Crocodiles,” a group of posh individuals who enjoyed the play of dabbling in magic. Some of them were strictly in it for the amusement and affiliation, while others were attuned to the actual working of magic. It is the latter group that Chorley has selected to run errands for him.Very quickly, we discover that whatever is taking place, it has lethal implications. As soon as members of the team enter the house of a former Little Crocodile, a gent named Richard Williams, a disturbance erupts. Peter and his partner Guleed emerge from their stake-out vehicle to see a woman burst through the tiles of the roof, blood smeared over her face. She leaps from the roof, and overpowers both of them, and makes her escape on foot. However, the blood on her face came from an attempt to kill Williams, by biting out his throat, and she missed.The incapacitated Williams is hospitalized in a secure facility, with a machine-gun wielding police constable on the outside of his room, guarding the door.The series title is “Rivers of London,” and whatever else that entails, we find that there are river gods and goddesses around. In fact, Peter is semi-keeping house with one of them, Beverly. They have the usual and customary physical relationship, but Beverly will manifest certain powers from time to time, from moving through rivers at will, to making some things happen quickly in the kitchen. Even so, she still exhibits normal concern for the well-being of her main squeeze, and he for her.There is quite a bit of conventional detective work that has to be done in tracking down Martin Chorley. Quite a lot of it is boring, such as sitting in surveillance locations, interviewing witnesses, and the necessary but tedious filing of paperwork and attending meetings. Enough attention is given to these details that we are aware of them, but we aren't beaten to death by police procedural trivia.That's not QUITE what my experience was with the magical / architectural trivia. As this was my first book in the series, and as a person who has spent a grand total (perhaps) of 72 hours in London, I found the descriptions of the history of some of the architecture to be other-than-illuminating. Now, SOME of this was necessary to the plot. However, other parts seemed solely designed to bewail the loss of a distinctive London-ness to the efforts of developers and financiers. There were also plenty of references to things that I'm sure would make sense to a person familiar with the London city streets, but which I found to be tedious.Along those lines, the book was filled with I can only suppose to be specialized slang terms that I've never heard. For example, a police car goes on pursuit with blues and twos. From the context, I'd say flashing blue lights and a siren, but that's just a guess. There are other similar slang expressions that take a bit of thinking for this Redneck Biker, but it only slowed me down; it didn't take me out of the story.A bit more problematic was the inclusion of untranslated Latin phrases. I had a half-year of Latin in 1966, and I was failing that. Fortunately, I discovered that there is an entire wiki, dedicated to the series, and a Google search for the Latin phrases yielded that site as the first result. The translations, and the context for the quote, were to be found there. While it was quite an interesting addition, I did not utilize the wiki further.Some of the events are funny, although perhaps not so much to those involved, but the thoughts of the POV character were often extremely amusing. Tossed in at random were any number of pop-culture references, such as the running joke “and one hard-boiled egg” line from “A Night At The Opera.” Unfortunately there were some references that were clearly meant to be humorous that went over my head; I'm not British enough (or at all).Finally, there were certain plot developments that DID require some knowledge of events from prior books in the series. Here are just two examples:Occasionally, late at night, I wonder whether this is true of Mama Thames and whether, perhaps, her blessing can make an old man kick his heroin habit and take up his trumpet again.Aaronovitch, Ben. Lies Sleeping (Rivers of London) (p. 80). DAW. Kindle Edition.The first time while I was buried underground, and later when Martin Chorley launched his abortive attack on Lady Ty.Aaronovitch, Ben. Lies Sleeping (Rivers of London) (p. 134). DAW. Kindle Edition.I have no idea what these quotes are referencing, or even if they ARE referencing something in an earlier book, or, in the case of the first quote, it's simply a jazz-insider reference.On the whole, though, it was a very enjoyable read. I think I would be MILDLY interested in pursuing the rest of the series, as long as it wasn't at the expense of my regular reading patterns.