Julie Kagawa has originally meant for her Iron Fey
books to be a trilogy, but The Iron Queen didn't exactly end on the happiest of notes, and The Iron Knight focuses on Prince Ash's quest to gain a soul and become mortal, so the metal and technology of the Iron Kingdom no longer poses a threat to him and can take his place at his beloved Meghan's side.
Assisted by his closest friend and sometime enemy and rival, Robin Goodfellow, better known as Puck, the self-serving cat Grimalkin, the Big Bad Wolf and a person from his past he thought lost forever, Ash has to make his way through all manner of trials down the River of Dreams, through the Briars, to the End of the World. It won't be easy, and it will certainly be dangerous, but Ash swore a vow that he would do everything in his power to be with his Iron Queen once more.
It was nice to have a book on Ash and Puck, and I got distinct echoes of Angel and Spike from Buffy the Vampire Slayer
in the trials Ash had to go through to gain his soul. An immortal creature without a conscience and remorse will have gone through a lot, and done a lot of cruel things to be sorry for. Interesting to see how Ash managed through it.