Apprentice enforcer Taya Mint investigates a kidnapping in Megastructure Seven Zero Three, uncovering a puzzle that leads to death and power struggles. As she navigates a world polluted by zealots and supernatural threats, Taya must face the monsters within humanity's artificial Eden to save an innocent life.

In his sophomore novel A Witch's Sin, Daniel B. Greene delivers a wildly imaginative, genre-blending thrill ride through a gritty cyberpunk world with a fresh supernatural twist. This ambitious sci-fi/fantasy mashup is a major step up for Greene, showcasing his growth as a writer and his ability to construct a uniquely compelling setting.

The story follows apprentice enforcer Taya Mint as she takes on one last case to earn her full license. What starts as a kidnapping investigation soon spirals into a dark conspiracy involving vampires, witches, and the sinister power brokers who run the towering Megastructure Taya calls home. To survive and protect the innocent, Taya must rely on unexpected allies and confront truths that challenge everything she thought she knew.

Greene's intricate worldbuilding is the novel's greatest strength. The Megastructure is a fascinatingly layered creation - a stratified, advertising-saturated techno-dystopia with supernatural secrets lurking in its depths. Futuristic elements like biomechanical upgrades and invasive holo-ads mesh surprisingly well with age-old occult forces. And Greene uses this richly textured setting as an effective backdrop to explore weighty themes of prejudice, fanaticism and class divides.

The story moves at a brisk clip, fueled by tense action sequences and an intriguing central mystery. Greene keeps readers guessing with well-timed revelations and plot twists. And while the shifts in tone and genre may not work for everyone, I found the gradual transition from cyberpunk detective story to supernatural thriller to be a clever bit of narrative sleight-of-hand.

On the character front, Taya makes for a tough, compelling protagonist. Greene gives her a convincing blend of vulnerability and grit. Her struggle to rebuild her life while coping with past trauma adds poignant emotions stakes to go with the physical peril. The supporting cast is equally interesting, from Taya's snarky vampire informant Quinn to the powerful and enigmatic witch Morrigan. Their shifting allegiances keep the interpersonal dynamics engaging.

Greene's prose has noticeably leveled up since his debut. The writing is leaner and more confident, with crisply descriptive action scenes and authentic-sounding dialogue. He still occasionally over-relies on italicized inner monologues, but overall the style suits the hard-boiled tone.

There are a few stumbles. Some of the social commentary feels a bit heavy-handed at times. The pacing flags slightly in the middle as Greene maneuvers his characters into place for the finale. And certain worldbuilding elements, like the origins of the vampires and the wider politics of the Megastructure, remain underdeveloped. But these are minor quibbles.

In the end, Greene swings for the fences with A Witch's Sin and mostly connects. By mashing up genres in clever ways and wrapping it all in a one-of-a-kind setting, he's crafted a fun, fast-paced thriller that serves as a showcase for his growing talents. It will be exciting to see where he takes the story and the world from here. Recommended for fans of genre-blending sf/f, action-packed plotlines, and protagonists who quip as well as they kick butt.

With a cool 3.74 average rating after nearly 400 reader reviews, A Witch's Sin seems to be satisfying Greene's existing fans and winning him some new ones. And it's easy to see why. While not without flaws, this novel marks a major evolution for Greene as a writer. It's an ambitious, inventive genre-bender that hints at even better things to come. I know I'll be eagerly awaiting the next chapters of Taya's story and Greene's career.