Anyone remember a show called "The Dresden Files"? It only lasted one season but it got me and a whole bunch of other people hooked on the books that inspired the show. On the subway I would often see three or four other people reading something from the series. Some of the books have also being converted to graphic novels. I don't know if I should use the word "popular", but those who like the books like them a lot.
So, I just finished reading "Small Favor". They stopped numbering the books at some point so I read this one out of order. It explains why I was a bit confused at first. It would help if you've read previous books in the series, but not completely required.
Wizard and private detective Harry Dresden is training his apprentice, Molly, at the Carpenter's house. They've sort of adopted Molly. She's being bombarded with snowballs and trying to keep up a magical shield when they get attacked by creatures called Gruffs. As in three billy goats gruff. Having defeated them Harry gets summoned by the police to investigate a building fire. He finds out that a local mafia kingpin and player in the magical realms was snatched from his panic room in the basement of this building. He's contacted by the queen of one of the major kingdoms of faeries to find the missing kingpin. Then attacked by more gruffs.
...and on like that. It takes awhile for the book to settle down and tell us what the fuck is going on. Turns out the Denarians are back. Remember the 30 pieces of silver used to pay off Judas for turning in Jesus? They're inhabited by demons. Those in possession of one of these coins has access to great powers. Actually, much more often the demon is in possession of the person. Sometimes the person has the will to keep control. They could be trying to recruit the head of a powerful mafia family into their ranks. Or he could be a step on to something they want even more.
The books in this series are about magical private detectives. Not in the same way as the Nightside books. These tend to be more light hearted. And Jim Butcher knows how to turn a phrase better than Simon R. Green. But both are series I recommend to people who enjoy some fantasy writing.
I recommend looking at the Wikipedia page for the series so you don't get out of order too much.