The third book of the Grimnoir Chronicles. Serious spoilers ahead for Hard Magic and Spellbound.
Indeed, after a flashback to the first fight with the Pathfinder, it opens with Faye secretly watching Whisper's funeral. Fortunately, she's noticed and manages to catch the Grimnoir elder who raised Whisper after her family was murdered. She wants him to try to train her, even though she knows he thinks she's too dangerous to live.
Meanwhile, Jake Sullivan is filling up an airship with all sorts of specialists to attack an Iron Guard position crucial to their plans. Because the stakes have gotten a lot higher.
It involves the discovery that someone can send a living thing through a communication spell, going into the Dead City, mazes without paths, Shanghai's criminal underground, a suit of armor, the reason why many countries had situations that got many Actives concentrated in small locations, and more.
And the grand finale to it all.