Baron Mordo possesses Iron Man turning him into the Iron Menace and escapes from the Dark Dimension, he plans to take over Super Hero City and Villainville. Wolverine, Falcon, Redwing and Abomination end up under Baron Mordo/Iron Man's control. Hulk, Silver Surfer, and Thor must team up with Doctor Strange and Valkyrie to form a team of Defenders and stop Baron Mordo's evil plot. Doctor Doom and M.O.D.O.K. reluctantly help them when Iron Menace takes control of Abomination.

When a smilodon is brought to Super Hero City from the Savage Land, a mysterious jungle lord named Ka-Zar shows up stating that the smilodon is actually his companion Zabu. When the Super Hero Squad encounter Ka-Zar, they learn of his mission and help him rescue Zabu. Meanwhile, Doctor Doom sees the Star Quartz (which will bind and merge any metal in the presence of Vibranium) around Zabu's neck and sends Toad, Thunderball, Sabretooth, and Batroc the Leaper to steal Zabu in a plot to reforge the Infinity Sword.