After the apparent sacrifice that separated Eddie Brock from Venom, Eddie tries to rebuild his life in silence, hiding far from the cities that once knew his name. Yet strange events begin spreading across the world: entire neighborhoods lose power, shadows move like living creatures, and survivors speak of voices whispering from the sky. Eddie quickly realizes the nightmare he thought had ended is only beginning.
Deep in a forgotten region of space, Knull — the ancient creator of the symbiotes — awakens fully from his prison. His rage has grown stronger after sensing that one fragment of Venom still exists on Earth. For Knull, this is not simply revenge; it is the moment to reclaim every symbiote ever created and turn Earth into the center of a new dark empire.
When black storms begin covering entire cities, small pieces of symbiote matter start bonding with humans at random, creating violent creatures that attack without warning. Governments fail to contain the outbreak. Eddie discovers that Venom is not completely gone — a weakened remnant survives inside him, struggling to regenerate while resisting Knull's call.
At the same time, Patrick Mulligan, now fully transformed by Toxin, emerges as one of the few beings capable of resisting Knull's control. Though he distrusts Eddie, both understand they cannot survive separately. Forced into an uneasy alliance, they begin searching for a hidden source of symbiote energy buried beneath an abandoned research facility connected to earlier experiments.
As Knull finally reaches Earth, the sky turns red-black and massive symbiote dragons descend over major cities. Venom returns in a more unstable form, stronger but constantly pulled toward his creator's will. Eddie faces his hardest battle yet: not just defeating Knull, but stopping Venom from surrendering to the ancient bond that links all symbiotes.
In the final confrontation, Eddie chooses to merge completely with Venom one last time, creating a new form powerful enough to challenge Knull directly. The battle tears through collapsing skyscrapers and burning skies, ending with Knull temporarily defeated — but not destroyed. In the final moments, a distant signal is sent into the multiverse, hinting that even larger forces have now noticed Earth.