The book begins with a training session of Molly's in the Carpenter back yard. She shields while the family assaults her with snowballs. The party is broken up when Gruffs from Summer attack Harry. Everyone escapes but Harry gets called by Murphy about a case.
Seems like someone trashed a building of Marcone's and threw around a lot of magic. While investigating, Harry is visited by Mab who informs him that Marcone has been taken. She charges him with finding and returning him safely.
A few visits and clues later, Harry and Thomas meet Hendrix and Miss Guard at a safe house. They are all attacked by a group of Denarians. Harry does what he does best and brings the front of the building down on them letting everyone escape. Guard was wounded badly and is recovering but gives Harry the information he needs to track Marcone.
Harry and Michael head to Union Station to pick up what they need. While there, the lights go out and Hobbs attack all in sight. Harry pulls off a cool bit of magic to cancel out the darkness that the Hobbs have conjured. The Archive/Ivy arrives to hopefully resolve things peacefully between Marcone and the Denarians.
A meeting is set at the aquarium and while Harry is talking to Nicodemus, a trap is sprung. Harry realizes in time and gets inside the giant magic circle before it closes and manages to take out several Denarians with the help of Kincade. Despite all he and Ivy can do, she is taken.
Harry plans to exchange all the coins and one of the three holy swords with Nicodemus to get Ivy back. They plan the exchange in the middle of lake Michigan, on an island that seems familiar to Harry.
Everyone double crosses everyone else but Harry manages to get Marcone and Ivy. While being extracted Michael is shot and critically wounded. Harry escapes into the woods and steals a boat and is rescued by Thomas. Thankfully everyone lives to fight another day.
"Likest thou jelly within thy doughnut?"