Having helped Sherlock Holmes and Dr. Watson solve the Whitechapel murders, Mary Jekyll leads a peaceful life in London in the company of her unusual friends - Beatrice Rappaccini, Catherine Moreau, Justine Frankenstein and Diana Hyde, Mary's sister. And of course, they can all count on Mrs. Poole, the permanent housekeeper, at any time. However, the peace is disturbed by a telegram informing about the abduction of Lucinda Van Helsing. Where is the girl and what did her father, Professor Van Helsing, do to her? In an attempt to find answers to these questions, members of the Athena club undertake a crazy voyage from Paris to Vienna, and then to Budapest. On this path, new allies, old enemies and, finally, a meeting with the secret “Society of Alchemists” await them...