The Six of Crows series, written by Leigh Bardugo, consists of two main books: Six of Crows and Crooked Kingdom.
These novels are set in the same universe as Bardugo’s earlier Grisha Trilogy, but they focus on a new cast of characters and a different storyline centered around a heist. While there are only two books specifically in the Six of Crows duology, Bardugo has expanded this universe further with additional works, including The Language of Thorns and the later King of Scars duology. However, for the core Six of Crows story, you will find just two primary novels.