Marvel's Ultimate Spider-Man Season 4, Episode 21: The Spider Slayers (1)

Hydra Attacks (1)

Peter Parker learns Doctor Octopus has teamed up with Arnim Zola and Hydra to attack the Tri-Carrier, leaving S.H.I.E.L.D. caught off-guard and Spider-Man left to single-handedly stop the assault. He assembles a new team, including an apprehensive Scarlet Spider, in order to stop the villains from taking over New York.

Hydra Attacks (2)

After being saved by Scarlet Spider following Arnim Zola's takeover of the S.H.I.E.L.D. Tri-Carrier, Spider-Man must work with him to liberate Manhattan and his fellow students from HYDRA's clutches. Even when they save Agent Venom and Iron Spider, they must also undo transformations of the HYDRA Goblins, avoid Doctor Octopus and Kraven the Hunter, and defeat Arnim Zola.

Miles from Home

After learning that Norman Osborn injected himself with an Anti-Goblin serum to prevent further transformations into Green Goblin following the last encounter, Doctor Octopus teams up with Baron Mordo and uses the Siege Perilous to pull the Ultimate Green Goblin from Miles Morales' universe into theirs so that HYDRA can be his master. Now Spider-Man and Miles have to work together with Doctor Strange to keep the demonic Goblin from using the Siege Perilous to destroy reality.

Iron Vulture

With the Siege Perilous destroyed in the aftermath of the fight with the Ultimate Green Goblin, Miles Morales is forced to stay in Spider-Man's reality until S.H.I.E.L.D. can find a way to get him and his world's Goblin back to their home. Now dubbed Kid Arachnid, he and Spider-Man must help Norman Osborn when he is targeted by Doctor Octopus and Vulture.

Lizards

Dr. Curt Connors has been turned into Lizard again. This time, he has a bite that turns anyone who is bitten into Lizards. The Triskelion goes under lockdown when Spider-Man's team and the S.H.I.E.L.D. Academy personnel get infected and attack Spider-Man. With help from an item in Nick Fury's office and with the help of Iron Spider, Leo Fitz, and Jemma Simmons, Spider-Man must work on an antidote in order to restore everyone to normal. Meanwhile, Agent Venom and Rhino guard Doctor Octopus' cell during the outbreak just in case he plans any escapes from his cell. Once everyone is cured, Spider-Man witnesses Doctor Octopus and Rhino making off with Agent Venom.

Double Agent Venom

After Doctor Octopus and Rhino have escaped the Triskelion with Agent Venom in their clutches, Spider-Man and Scarlet Spider track them to the recently-returned HYDRA Island as Doctor Octopus and Arnim Zola work to separate the Venom symbiote from Flash Thompson. In order to get to Flash, Spider-Man and Scarlet Spider have to fight their way past Kraven the Hunter and the HYDRA Agents. Ock Manages to succeed in separating the symbiote from Flash, giving to Kraven, who becomes a lion-like Venom. However, Flash is able to coerce the symbiote back to him as they understand each other. As a result of the re-fusion, Agent Venom gains a new look.

Beached

Spider-Man, Iron Spider, Agent Venom, Kid Arachnid, and Scarlet Spider have been looking for signs on where Doctor Octopus is hiding out. Upon Spider-Man and Iron Spider being ambushed by Vulture, they follow him to a nearby island where they are attacked by clones of Sandman. As Spider-Man fights the Sandman clones, Iron Spider stumbles upon a secret laboratory where Doctor Octopus has captured Sandman and cloned him so that he can find the "Ultimate Sandman" that will join the Sinister Six. After Sandman is rescued and Doctor Octopus escapes, Spider-Man allows Sandman to spread out around the Triskelion.

Anti-Venom

Spider-Man and Agent Venom have been busting villains like Beetle, Grizzly, Shocker, and Shriek where they suspect that they might be candidates for Doctor Octopus' Sinister Six. Arnim Zola recruits Michael Morbius to work on a new symbiote. When Spider-Man, Agent Venom, and Harry Osborn in the Patrioteer armor track them down, they are caught off-guard when they release the Anti-Venom symbiote which possesses Harry and does not have any of the symbiote weaknesses. The resulting battle leaves Agent Venom injured and Harry in a coma.

Force of Nature

During a drought, Spider-Man, Iron Spider, Kid Arachnid, and Scarlet Spider answer a distress signal that takes them to an abandoned mall in Queens. They find an empty air-tight room containing Hydro-Man who has a past with Nick Fury. While transporting him to the Triskelion, Iron Spider find that Hydro-Man is not a good guy where the fight with him causes an emergency landing near Aunt May's house. While Spider-Man, Iron Spider, and Kid Arachnid fight Hydro-Man, Scarlet Spider works to protect Aunt May who ends up naming him Ben. Once Hydro-Man is defeated where the resulting battle watered Aunt May's lawn, Spider-Man gets word that the Quinjet carrying Hydro-Man back to his cell was intercepted causing Spider-Man to speculate that Doctor Octopus has gotten Hydro-Man on his side.

The New Sinister Six (1)

Spider-Man faces the culmination of all Doc Ock's evil machinations when the new Sinister Six assaults the Web Warriors and S.H.I.E.L.D. Academy at the Triskelion.

The New Sinister Six (2)

When Doc Ock learns that the key to a device that will retrieve Hydra Island is at Aunt May's house, Spider-Man must fight to protect his family.

Agent Web

When a battered Nova asks for help finding Nick Fury, Spider-Man tracks him to the dangerous ruins of an ancient city.

The Symbiote Saga (1)

Spider-Man and Agent Venom discovered Hydra and Morbius' plan to create a new and improved Venom Bomb.

The Symbiote Saga (2)

Spider-Man, Captain America and S.H.I.E.L.D Academy must band together to save New York.

The Symbiote Saga (3)

Spider-Man and his fellow heroes have to Morbius and his plan to use the Carnage Queen as a weapon.

Return to the Spider-Verse (1)

Spider-Man and Kid Arachnid travel to alternate dimensions to gather the shards from the broken Siege Perilous.

Return to the Spider-Verse (2)

Spider-Man and Miles, tracking the missing pieces of the Siege Perilous, travel to a tropical Pirate dimension where they meet Web Beard, the Spider-Pirate, and encourage him and his old team to work together to save themselves from the dreaded Kraken.

Return to the Spider-Verse (3)

Spider-Man and Kid Arachnid arrive in the Noir Universe where they have to prevent Mr. Negative from using the Siege Perilous to drain all the life and color out of the world.

Return to the Spider-Verse (4)

Spider-Man, having collected all of the shards of the Siege Perilous, returns to Miles Morales' universe and confronts Wolf Spider.

Strange Little Halloween

Trick-or-treaters start turning into monsters and Spider-Man, Dr. Strange and Ant-Man must team up to stop Baron Mordo.

The Spider Slayers (2)

Spider-Man and Scarlet Spider have to infiltrate the sunken Hydra Island so Scarlet can destroy the lab that created him.

The Spider Slayers (3)

Spider-Man puts the Triskelion on lockdown when a mysterious villain begins to take out the heroes one at a time.

21 min

The Moon Knight Before Christmas

Spider-Man house sits on Christmas Eve and is forced to team up with Moon Knight to defend the home from the new Mysterio.

21 min

Graduation Day (1)

Spidey must track down Ock before he harms Aunt May.

21 min

Graduation Day (2)

Peter Parker must find a way to stop Doctor Octopus and the Superior Sinister Six from destroying all of the heroes in New York and taking over the world.

21 min