A few weeks after Carnage's attack on Manhattan, Eddie Brock has been staying at Liz Allan's house and wrestling with the guilt of having unleashed Knull to save his son, Dylan. Contacted by the Avengers, Eddie is brought to Avengers Mountain and offered a membership by Captain America. Before Eddie can reply, the Dark Carnage symbiote reveals it survived being absorbed and had been imbued with the persona of the original Carnage symbiote; declaring its intent to take over Eddie's body as revenge for the death of Cletus Kasady. Asking for time to consider the Avengers' offer, Eddie charters a Quinjet and returns to the Isla de Huesos - the tropical island where he and the Venom symbiote had lived years ago after seemingly killing Spider-Man - intending to finish off Carnage once-and-for-all. As the Quinjet reaches the island, the Carnageized Grendel symbiote crashes it and assimilates the Venom symbiote, Eddie challenging it to a final showdown.
Meanwhile, Dylan suffers from nightmares of Knull, with Sleeper chastizing him for having kept a surviving piece of Norman Osborn's offshoot of the Carnageized Grendel symbiote.
Arming himself at an old military bunker, Eddie offers the Carnageized Grendel symbiote - which takes over every animal on the island - an ultimatum: return the Venom symbiote to him and he will give it the Isla de Huesos to do with as it pleases, or he will raze the island to the ground to kill it. Rejecting Eddie's ultimatum, the Carnageized Grendel symbiote attempts to bond with him, forcing him to cut off his left hand to escape. As a storm strikes the island, Eddie climbs Isla de Huesos' mountain; the Carnageized Grendel symbiote bonding to him just before being struck by lightning, the shock separating it from Eddie and the Venom symbiote.
The Carnageized Grendel symbiote bonds to Eddie, tormenting him with a nightmare of his worst fears coming to pass before taking over his body. Seeking to confront Knull by connecting to the Symbiote Hive through his piece of the Carnageized Grendel symbiote, Dylan witnesses these events and offers to help the Venom symbiote; empowering and remote-piloting it to save Eddie. Despite being briefly caught off-guard, Carnage overpowered Venom and psychically tortured Dylan, attempting to use the symbiote's offshoot to take over him. With encouragement from Eddie, Dylan was able to resist Carnage's will, destroy the symbiote's offshoot, and blast its main body off Eddie - seemingly killing it. Eddie rebonded to the symbiote, which was unable to grow back his severed hand; and Dylan subsequently got Liz Allan to contact the Avengers, who retrieved Eddie from the island. Taken back to Avengers Mountain, Eddie decided to come clean about his mistakes and warn them about the coming of Knull.
Unbeknownst to Eddie, the Carnage symbiote survived Dylan's attempt to destroy it and reconstituted itself, taking on the form of a shark to escape the Isla de Huesos and return to the mainland.
- The events of Venom Island happen concurrently to the events of Scream: Curse of Carnage #1 - Scream: Curse of Carnage #5.