Just picked this up from a used bookstore shelf on a whim, and ended up reading it in one sitting. The main plot follows this guy, Kaelen, who's a 'shadow runner'—basically a courier for the magical black market in a cyberpunk-ish city called Veridia. The inciting incident is him accidentally picking up a data crystal that doesn't just contain secrets, but is a fragmented soul of a dead archmage. The corporation that killed the mage, OmniCorp, wants it to fuel their immortality project, so Kaelen's on the run.
The book isn't just a chase, though. The soul in the crystal starts talking to him, offering power and knowledge in exchange for help getting revenge. A lot of the middle section deals with Kaelen's internal conflict—he's used to being a selfish survivor, but the mage's memories are bleeding into his own, making him question everything. There's a great sequence where he has to navigate the vertical slums of the city's lower levels, using his knowledge of the shadow networks, while being hunted by both corporate hit-squads and rival runners who've been bought off.
The final act hinges on a choice: deliver the crystal to a resistance group that wants to destroy it (and potentially kill the mage's soul for good), or use its power himself to take down OmniCorp's local headquarters, which would mean fusing with the soul and losing part of himself. It ends ambiguously—he chooses the fusion, the tower falls, but the last chapter is from the perspective of a different runner finding Kaelen's modified jacket in the rubble, hinting he's become something new and maybe not entirely in control. It’s a solid blend of heist and existential horror.