During the summer vacations, the three friends are about to take a trip together to Romania, where they are allowed to complete an internship on the film set of "Dracula Rises", arranged for them by Peter's father, who is responsible for the special effects during the filming. No sooner do they arrive in Transylvania than mysterious events begin to pile up at Countess Codrina's old castle, which serves as the original setting for the film. The three detectives want to find out what all this may have to do with a boy who has been missing for over 50 years, a mysterious brotherhood and an enigmatic undead. Soon, not only the filming and Peter's relationship with his father are at stake, but also the friendship of the three investigators.

"Solve the riddle of the Sphinx or someone will lose their life." - then the line goes dead. Justus, Peter and Bob are breathless. But the three detectives from Rocky Beach have no idea that they are already in the middle of their next case. A secret organization, a lost treasure and a legendary island from which no one has ever returned alive demand all of the three detectives' skills.

A call for help from gallery owner Mr. Prentice leads the three detectives into a new adventure: his apartment is said to be haunted. When the Carpathian dog, a valuable work of art, is also stolen, events spiral out of control because all the residents have a motive. As the suspects are eliminated one by one, the three detectives find themselves in the middle of their most exciting case yet.