A supernatural serial killer preying on women in our world draws Beck and Caul into the shadowy realm of the Underside. Jonas Beck, a centuries-old werewolf who has renounced his dark nature, and Mercedes “Caul” Guillane, a psychic with unique strength, must combine their abilities to confront a killer draining victims of their life force. Their pursuit leads them into the Underside, a dimension where nightmares breed, forcing Caul to face legendary monsters and both heroes to navigate a treacherous landscape of deception and death. They stand against evil in all its forms, from the depths of the human heart to the ancient creatures of the Underside, in a battle for survival against the killer in "The Underside of Fear".

The premise sets up a classic urban fantasy narrative blending supernatural elements with a detective-style investigation. The inclusion of a werewolf, a psychic, and a host of mythical creatures suggests a rich, albeit potentially crowded, world. The focus on a serial killer and the descent into a nightmare realm points towards a story with significant horror and suspense elements. The narrative appears to prioritize action and the confrontation of monstrous threats, likely appealing to readers who enjoy dark fantasy with a strong sense of peril.