In the realm of dark romance, "Taking Her Innocence (Killer of Kings 1)" by Sam Crescent promises a blend of intensity, moral ambiguity, and raw emotional drama that occasionally borders on the controversial. This novel introduces us to a world enshrouded in violence and desire, weaving a complex narrative that challenges the reader’s perceptions of right and wrong.

The story centers around Viper, a hitman known for his ruthless efficiency and cold demeanor. From the onset, his character is painted as enigmatic and formidable, drawing the reader into a deep curiosity about his past and the life events that shaped his merciless nature. Viper is tasked with the elimination of a target, but this mission diverts significantly when he encounters the innocent Shay, whose relationship to his target complicates his mission exponentially.

Shay is portrayed as the quintessential figure of purity and naivety, thrown violently into the chaotic world of Viper. Crescent deftly explores the dynamics of power and possession through the interactions between these two central characters. Shay’s transformation throughout the novel is both compelling and, at times, starkly jarring, as she is propelled from innocence into the turbulent world of crime and retribution.

The author excels in crafting a steamy, though often uncomfortable, relationship dynamic between Viper and Shay. The concept of 'innocence taken' is aggressively pursued, and it’s here that Crescent boldly treads the line between consent and coercion. This theme might not sit comfortably with all readers, particularly those sensitive to issues of consent and power dynamics in romantic or sexual relationships. The psychological depth added to the characters, however, does provide a layer of complexity that invites readers to explore beneath the surface of these potentially problematic elements.

As far as the narrative structure is concerned, Crescent maintains a crisp pace, skillfully intertwining suspense with emotional developments. The dual perspective approach gives insight into both Viper and Shay’s thoughts, offering a well-rounded view of their inner turmoil. Readers are treated to a meticulous exploration of Viper’s conflicting emotions, teetering between his ingrained harshness and a burgeoning protective sentiment towards Shay.

Though primarily a romance, the book does not shy away from violent and graphic descriptions. The details of Viper’s occupation bring a gritty realism to the story, and Crescent does not gloss over the bleakness of the criminal underworld. The inclusion of secondary characters adds depth to the story, providing varying perspectives on morality and survival. These characters enhance the narrative, contributing to the palpable tension and complexity of the relationships depicted.

One of the more commendable aspects of Crescent’s writing is her ability to evoke a spectrum of emotions from the reader. From discomfort and shock to empathy and anticipation, the emotional engagement is potent and constant. The sexual elements of the story, while explicit and often dominant, are integral to understanding the characters’ evolution and the power exchange between them.

However, "Taking Her Innocence" is not without its flaws. Some readers might find the development of the romantic relationship rushed or underexplored. The transformation from captivity to affection, particularly on Shay’s part, might strike some as implausible, requiring a willingness to suspend disbelief to fully immerse in the story. Furthermore, the heavier themes might benefit from a more nuanced exploration to avoid alienation of those uncomfortable with the darker aspects of the narrative.

Overall, Sam Crescent's "Taking Her Innocence" delivers a complex, visceral reading experience that is sure to resonate with fans of dark romance. The novel adeptly mixes elements of danger, passion, and transformation, although it ventures into areas that some might find morally and ethically challenging. It stands as a provocative start to the 'Killer of Kings' series, setting a robust foundation for future explorations of its darkly entwined characters.

In conclusion, this book is recommended for those who appreciate a romance that challenges traditional boundaries, with the caveat that it is not for the faint of heart. Crescent’s writing captivates and confronts, ensuring that her readers are engaged, affected, and, ultimately, transformed by her narrative.