A fallen demon in Berlin builds an operating system for desire—and declares war on Hell, regulators, and the myth of free will.

When Serris Vale is cast out of Hell for a heartbeat of mercy, she lands in Berlin with horns intact, wings burned, and a plan sharp enough to cut the city open. Nights become laboratories. Clubs become churches. With a brilliant, reluctant coder and a ruthless dealmaker, Serris births Lilith—a machine that doesn’t guess what people want; it persuades them.

As Lilith wires itself into dating apps, storefronts, and travel engines, Berlin starts to hum to Serris’s frequency: desire as policy, appetite with governance. That’s when the hunters arrive. Hell’s Treasurer brings a coin and an ultimatum. A task force braids her name into subpoenas. And Björn Nilsson, a detective with winter-blue eyes and inconvenient debts, keeps showing up on the threshold between arrest and confession.

Serris can earn her way back below—or crown herself topside. Either way, someone pays.

NEON SIN is a dark techno-noir of temptation and systems, where algorithms learn manners, angels keep ledgers, and love feels like a zero-day exploit.

Read if you love: morally feral heroines, sentient systems with wicked wit, urban fantasy wired with cyberpunk nerve, enemies-to-lovers heat, and cities that bite back.