There’s a longer plot in these books. What happened in the end of the first, is picked right up again in the beginning of the second and the characters… well, they stay true to themselves and the changes they’ve had to gone through. Some lessons take longer to learn than the others. Like in Rivers of London there’s two plot threads advancing simultaneously in this book. There’s the long plot about Peter growing as a magical apprentice and then there’s the short plot and an incidental murder that needs solving. At this point you’re either reading the book for the characters or the mystery, and let’s just say that I can’t remember anything about the short plot. Like all good show runners know, there needs to be a big bad that the hero has to strive to defeat. Make it impossible and there’s no point for the series, but make it too easy and it’s boring. Aaronovitch went with the limited exposure and only gave the frayed end of a very thin thread for Peter and his master to follow. Unlike the YA authors, the young apprentice hero isn’t expected to save the world all on his own a couple of months after he’s learned his first spell. He has help, which in Peter’s case means the Metropolitan Police and Nightingale. The adults supervise the younglings.