Mark of the Vampire

Sir Karell Borotyn is found murdered in his own house, with two tiny pinpoint wounds on his neck. Attending the doctor Dr. Doskil and Sir Karell's friend Baron Otto von Zinden quickly suspect a vampire attack, while Prague police Inspector Neumann remains skeptical.

The doctor and Baron Otto entertain the possibility that Count Mora and his daughter Luna are involved, hinting at supernatural causes. However, Inspector Neumann refuses to believe in vampires, keeping the mystery unresolved.

Irena, Sir Karell's daughter, is marked as the Count's next target and faces increasing danger. The threat prompts the uneasy alliance of Zelen, Otto, and Neumann to protect her.

Professor Zelen, an expert on vampires and occult practices, arrives to prevent Irena's death and uncover the truth behind the vampire attacks. He immediately joins the others in their effort to thwart the escalating danger.

During the night, Zelen, Baron Otto, and Inspector Neumann descend into the ruined parts of the castle in search of the undead. The dim corridors and crumbling halls provide the setting for their tense pursuit.

During the hunt, Zelen hypnotizes Baron Otto and asks him to relive the night of Sir Karell's murder. The technique is meant to uncover clues and unmask the killer.

It is revealed that the so-called vampires are hired actors, and the entire experience has been a carefully staged charade orchestrated by Zelen. The aim was to coerce the real murderer into revealing himself.

Zelen acknowledges that the elaborate ruse failed to produce the intended confession. The failure leaves the team without a clear lead, prompting a new tactic.

Zelen, Irena, and another actor compel the hypnotized Baron to re-enact the murder on the spot. The dramatic reenactment serves to expose the true culprit through his own words and actions.

During the reenactment, Baron Otto reveals his motive: he wished to marry Irena, but Karell's opposition blocked the match. He admits to staging the murder to resemble a vampire attack and to frame others.

The confession leads to Baron Otto's arrest, ending his scheme and sparing Irena from further danger. The case appears resolved as the true culprit is brought to justice.

Irena explains the entire plot to her fiancé Fedor, who had believed the vampires were real. He is relieved to learn he was not involved and that the danger has been resolved.

The actors begin packing up their supplies as the charade winds down. Count Mora proclaims that the vampire theme will inspire a new act, saying he will be the vampire and that he gave all of himself.

Luna and the rest of the troupe respond with mixed enthusiasm to Mora's bold plan, signaling lingering doubts about the viability of the new act. Their skepticism hints at tension between artifice and reality in the wake of the night's revelations.