Six of Crows by Leigh Bardugo

Six of Crows
In a sprawling city reminiscent of a cross between Amsterdam and Dickensian London, Kaz Brekker runs his gang ruthlessly, if only to keep them alive.
Then he's offered a large sum of money to retrieve a man who might have created a dangerous drug. Accepting the mission, he takes with him a group of teens with singular talents. Inez is a former acrobat who can move as silently as a cat. Jesper is a brash gunslinger. Wyland is an explosives expert. Nina is a seductive young woman with the power to kill. Matthias is a young man with interior knowledge of their destination, but needs to broken out of a hellish prison.
Each character has their own baggage. It's a quest and a heist all in one. Kaz and Inez are meant for one another, but there's a lot standing between them. The others are given their moments and budding relationships and each one is intriguing. This story never gets dull. One of the best character-driven fantasies I've ever read.