Louis Hartmann joins forces with the members of the Arne Detective Agency to investigate his father's murder.

Lynn remembers the time she first met Arne and hired him to help investigate her father's suspicious behavior.

Arne makes a shocking discovery about Lynn's father and Gordon reveals the dark truth of the Reinweiß mansion.

Lynn and Arne are both troubled by surprise encounters that threaten to alter the course of the investigation.

Lynn and Arne assemble the servants to review the clues and sniff out the killers through deductive reasoning.

A distraught mermaid arrives at the detective agency searching for the reason why her lover tried to kill her.

Arne tracks down a jewel thief while Lynn investigates a series of disappearances connected to an art museum.

Lynn and Arne trace the mysteries of the missing men and lost piece of jewelry to their shocking conclusions.

Arne and Lynn are asked to investigate a man who appears to have started cheating on his wife after an injury.

Arne decides to investigate a locked-room murder on a whim and soon realizes that it may not be what it seems.

Arne uncovers a disturbing connection between all five of the cases investigated by the Arne Detective Agency.