The American search party finds Charly unconscious and discovers the dead bodies of the other airmen, marked by strange wounds.

Charly, tortured by the spies, confirms the existence of the H-bomb before being dumped back on the island, where he becomes a threat to Yukari and Junko, a local doctor.

As the situation escalates, Nagumo and his allies are captured by the spies and Annabelle, who reveals her ultimate plan to use the insects for global genocide.

Nagumo and the survivors attempt to evacuate the island, but the Americans, led by Gordon, plan to detonate the H-bomb to cover up the incident and eliminate the insect threat.

Despite Nagumo’s desperate attempts to prevent the detonation, the film ends on a note of impending doom, questioning humanity's future and the destructive potential of scientific experimentation gone awry.

"[9] Sight & Sound described Genocide as an "accident of a film" that "plays mostly as a national symptom, in a legacy of scenarios devised both to make sense of, and to reduce to pulp the memories of nuclear heat-death".