In "Pluto," Gesicht, an android detective working for Europol, is assigned to investigate the murder of Montblanc, a highly respected veteran robot. While the case initially points toward another robot as the suspect, Montblanc's status as a key figure in the fight for robot rights adds layers of complexity. Robots are generally programmed with safeguards preventing them from harming humans, with the exception of a single, unexplained incident that occurred eight years prior. The murder scene, which shows no signs of human involvement and shares striking similarities with that earlier event, leads Gesicht to believe that one entity—whether human or robotic—may be responsible for both killings.
Not long after Montblanc's death, another former elite war robot is also killed under mysterious circumstances. Gesicht begins to recognize a pattern: both victims were among the seven most powerful war machines ever created. To prevent the killer from targeting the remaining five veterans, Gesicht joins forces with Atom, a highly advanced android who looks like a human child. Together, they work to identify the culprit behind these murders and stop the threat from causing further harm to society.