- Fantastic Four (First full appearance)
- Lucia von Bardas (Death) (Final appearance)
- Doctor Doom (Victor von Doom) (First appearance)
- Masters of Evil (Mentioned)
- Doombots (First appearance)
- Eitri (Mentioned)
- Thor (Thor Odinson) (Appears on a computer screen, TV, or hologram only)
- Ant-Man/Giant-Man (Hank Pym) (Appears on a computer screen, TV, or hologram only)
- Princess Ravonna
Races and Species:
- Avengers Identicard
- Iron Man Armor
- Fantastic Four Uniforms
- Thorbuster (Mentioned)
- Uru (Mentioned)
- Mjolnir (Appears on a computer screen, TV, or hologram only)
- Captain America's Shield (Appears on a computer screen, TV, or hologram only)
- Captain America's Uniform
- Ant-Man's Suit (Appears on a computer screen, TV, or hologram only)
- Ant-Man's Helmet (Appears on a computer screen, TV, or hologram only)
- Hawkeye's Bow and Trick Arrows
- Hawkeye's Suit
- Doctor Doom's Armor
- Panther Habit
- Vibranium Energy Daggers
Lucia von Bardas is reviewing the heroes and threat levels for her Master, and as Thor and Ant-Man are not accounted for, she recommends the attack be postponed. Dr. Doom refuses to delay - if the Avengers get in the way, they must be... destroyed!
The Thing and the Human Torch visit the Avengers Mansion for a friendly game of poker. As soon as the Hulk sees the Thing, he charges.
Meanwhile Iron Man and Wasp are paying a call on the Baxter Building. Stark flirts with the Invisible Woman. Wasp and the Invisible Woman pair off for "girl talk" while Iron Man joins Mr. Fantastic in Reed's lab, where he's working on a cure for Ravonna, the consort of Kang.
Meanwhile, the poker game is underway, but not for long before the Hulk attacks the Thing... again. Thor stayed behind in Asgard, more or less. The Black Panther had four aces, in any case.
Back in the lab, Iron Man confirms that Hank Pym is on a leave of absence from the Avengers, and offers Mr. Fantastic some relationship advice. Reed observes how distant the Invisible Woman has been the last few weeks.
Doom gives the order for the attack to begin, and Doombots attack at both the Baxter Building and the Avengers Mansion, having infiltrated both grounds undetected. The Doombots do well, but both Mr. Fantastic and the Black Panther question why the timing of the attack.
After a short while, the remaining Doombots are shut down by Dr. Doom. Wasp and the Invisible Woman are captured, The Doombots go into self-destruct mode, forming a daisy chain to increase their destructive power. Mr. Fantastic and the Black Panther focus on disarming the Doombots, while the Iron Man goes off in pursuit.
Iron Man catches the aircraft and boards it briefly, but his armor is fried by Von Bardas, and he is forced to return to the Baxter Building. The others join him, and a discussion ensues on how to proceed, while the Captain American Skrull watches and assesses.
On the one hand, Dr. Doom is certain to have set a trap for the Fantastic Four, on top of which they can't invade a sovereign country. On the other hand, Iron Man has a plan...
Meanwhile, the Wasp and the Invisible Woman are in a prison device inside of Castle Von Doom, presumably in Latveria. Wasp wakes, and awakens the Invisible Woman. Dr. Doom is calibrating his machines, and ignores the Wasp's "prattle" and bluster.
The Avengers' Quinjet, with the Human Torch outside, is closing on the castle, and Von Bardas activates its missile defenses. The Quinjet and the Human Torch evade the barrage, but retreat out of Latverian airspace.
Suddenly, Dr. Doom whirls and fires - Iron Man, the Black Panther, and Mr. Fantastic had infiltrate into the castle, undetected until then. More Doombots enter the fray, as do the other Avengers and the balance of the Fantastic Four.
Dr. Doom fights the combined team to a standstill, then frees the Wasp and the Invisible Woman, and commands them to go. Mr. Fantastic questions Doom as to why, and Iron Man reminds Doom that this isn't over - the fight will continue another day.
As the Avengers and the Fantastic Four travel back to the United States, Dr, Doom is reviewing the data he got on Wasp and the Invisible Woman, revealing the Invisible Woman to be a Skrull!
- This episode is based on Avengers #25, and Avengers #154-#156.
- Captain America was replaced by a Skrull in the season finale episode "A Day Unlike Any Other".
- Starting from this season, the series has a new opening;
- Much like the one here, another Susan Storm was replaced by a Skrull. In this case however, not only are everyone except for Doctor Doom unaware, but it serves as another foreshadowing to the series' coming Secret Invasion storyline.