As the heroes begin arriving, Nova asks about Diablo's powers and what they might be facing. The Vision explains that the alchemist carries a number of vials which can create a series of different effects. He also can control inorganic matter along with some forms of organics. As the android relays the information to Nova, Diablo continues his assault on the armored Avenger and captures him by controlling a brick wall.

Richard Rider finds himself being chased by a fire creature as the Vision explains that the master of chemicals can also summon elemental creatures along with being able to control people through hypnotic suggestion. Sue Storm asks the artificial humanoid for any ideas on why Diablo is attacking them. The Vision recalls that he had visited the alchemist earlier in the day and he appeared to be upset that he has been unable to free his loved one from her frozen state. The man without emotions wonders if Diablo's frustration has caused him to become mentally unstable.

Meanwhile, Captain America tries to contact Thor who is in a furious battle with an animated building which has taken a humanoid shape! The captain's call is interrupted by a transmission from Iron Man. Tony Stark informs Steve Rogers that he is being held hostage in a basement by Diablo. The kidnapper overhears them and the three begin trying to figure out what happened as Diablo cannot recall recent events.

He is able to remember feeling fine earlier in the day but then began having trouble breathing. It was followed by a growing hatred of the Avengers and he remembers knocking Iron Man unconscious with sleeping gas created by an air elemental. Diablo begins remembering events from even earlier. He had been using another air elemental to spy on the Avengers in their headquarters. He had been watching a conversation between Thor and the Vision as they discussed emotions. During their talk, the two Avengers feel a change in the air pressure from Diablo's elemental. The alchemist spy was forced to leave and move onto another room.

In one of the training rooms, Diablo witnesses Captain America, Invisible Woman and Nova practicing combat techniques. Sue Storm advises Richard Rider to attack at full power, otherwise he'll lose to Steve Rogers. Nova uses an energy blast to send cap's shield flying and attempts to hit Steve with his fist. The Star-Spangled Avenger easily dodges the punches and skillfully moves the Human Rocket into standing exactly where his shield was coming down. Nova is knocked to the ground when the shield hits him in the back of his helmet!

As Nova decides to take a cold shower and try to forget the morning happened, Steve and Sue begin talking about leadership of the Avengers. Before they can get too far into their conversation, Sue receives an incoming holographic message from Reed Richards.

In the present, Tony Stark is able to regain communications with Captain America from Diablo's basement. Iron Man informs Steve that it appears they must have teleported to the basement so tracking him will be difficult. Suddenly, the transmission stops and Cap realizes the air temperature has dropped. A storm has suddenly developed and the Avengers look up to find Thor's cape and a figure falling to the ground! Sue is able to generate a force bubble to catch them in time as Cap and the Black Widow rush over to help.

They quickly realize it is the building creature and only Thor's cape that had landed. Captain America immediately calls in Thor and Nova to fight the monster. Nova answers the call and rushes to their aid. Unfortunately, he is also bringing the flame creature that has been following him! As the Vision, Black Widow and Nova fight the elementals, there is a rumbling and suddenly Thor smashes through the brick creature. With the flame elemental remaining, the Avengers begin a full attack on their foe.

Meanwhile, Diablo and Iron Man are debating the outcome of the battle. Tony is confident the Avengers will win while Diablo is saddened by the idea that they are fighting for nothing. As the crazed alchemist shows Tony Stark projections of recordings he made while spying on them, the Vision appears. The android had been able to track the armored Avenger's transmissions to the basement.

After scanning the scientist's body chemistry, the Vision realizes that the villain has been manipulated like the other people they've been tracking around the world. He informs Diablo that his emotions have been controlled so he only feels despair. Upon hearing the truth, the alchemist becomes angry as he realizes who has been in control. Through sheer willpower, the king of chemicals purges a black energy being from his body.

Diablo explains to the two Avengers that the creature is a demon known as D'Spayre. The black monster feeds on negative emotions but no longer has power over the scientist now that he is aware of his presence. Realizing he is defeated, D'Spayre disappears in a small burst of dark energy.

A holgraphic message from the Invisible Woman is received by the Vision. Iron Man informs her that Diablo was not responsible for his actions and they should let him go. Before they leave, Tony Stark turns and punches Diablo in the jaw. Smiling, he helps the alchemist up and tells him that he'd been wanting to do that all day!