Gesicht, an android police detective for Europol, is assigned to find the murderer of Montblanc, a retired war hero robot. While it seems only a robot could have committed this crime, the killing of a prominent robot rights activist raises doubts about the culprit's identity. Indeed, aside from an isolated and unexplained incident eight years ago, robots are programmed to be incapable of killing humans. However, the absence of human evidence at the crime scene and the similarity in modus operandi lead Gesicht to suspect that the two killers might be the same entity—whether human or robot. Shortly after Montblanc's death, another retired elite war robot is mysteriously killed. Gesicht notices a pattern in the selection of victims: both deceased robots belonged to a group of the seven most powerful war machines ever designed. Determined to stop the murderer from eliminating the five remaining veterans, Gesicht seeks help from Atom, a cutting-edge android who resembles a human boy. The duo must now hunt down the rogue killer before the series of murders continues, lest the very fabric of society suffer irreparable damage.