After a string of gruesome murders rocks Crowncrest's lower districts—victims found with surgically removed organs and suspicious marks dismissed by authorities as "robbery gone wrong"—Detective Inspector Harwick finds himself politically muzzled when his investigation begins pointing toward the city's elite. Defying orders, he secretly recruits the party as undercover agents to continue his work, providing them access to the half-dozen crime scenes where each victim was found in shadowy alleyways with identical horrific injuries. As the investigators piece together evidence from each murder scene—from strange bite marks to the peculiar lack of blood—they discover disturbing connections leading to the aristocratic circle of the reclusive Lord Thorne. Each victim had recently served at exclusive gatherings hosted by the nobleman, who returned several months ago from mysterious foreign travels, and witnesses report seeing aristocratic figures lingering near crime scenes. When invitations to Lord Thorne's upcoming masquerade ball arrive in Crowncrest's high society, Harwick secures false identities for the investigators to infiltrate this most exclusive of gatherings.

The masquerade ball at Lord Thorne's opulent manor presents a dangerous game of deception, with the investigators navigating elaborate political intrigues and forbidden romances while maintaining their covers among Crowncrest's suspicious elite. Behind ornate masks and flowing champagne lies a deadly secret—servants whisper about the "special guests" who disappear during the night, and Lord Thorne's personal physician is observed collecting vials of red liquid from selected attendees. As the night progresses, the party must carefully gather evidence from reluctant servants, intercept cryptic messages between aristocrats, and potentially catch glimpses of Lord Thorne's strange behavior—his aversion to certain foods, his pallid complexion, and his absence from daylight gatherings. The challenge escalates when a serving girl reveals a hidden passage beneath the ballroom, tempting the investigators to break away from the festivities to explore the manor's forbidden chambers, where the full horrific truth awaits: Lord Thorne is not simply a murderer but something far more monstrous, and his masquerade conceals more than just aristocratic indiscretions.