A desperate businessman is given incredible abilities for only one reason: revenge on Tony Stark.
Simon WIlliams, the owner of a technology company focusing on alternate energy sources, visits Tony Stark to discuss how he has been slowly buying shares in his company. Stark informs him that, as of fifteen minutes before their meeting, he has become the majority share holder.
Outraged and desperate, Williams turns to his brother, the HYDRA agent known as the Grim Reaper. While the two share clear baggage, the Reaper promises to help Simon by introducing him to AIM, an underground weapons research group. He meets the bizarre M.O.D.O.C., a mental organism designed only for conquest. M.O.D.O.C. promises to give Simon powers beyond his imagination, though the process is dangerous and could turn him into something not quite human. Concerned by the implications, but feeling like he has no choice, Simon agrees to the experiments.
In Avengers Mansion, Captain America is visited by Nick Fury. The two visit a secret SHIELD base located beneath an innocent looking New York City barber shop. There, Fury reveals that he has Captain America's original motorcycle used during World War II, a gift from his father. Captain America realizes that Fury is the son of Jack Fury, the leader of the Howling Commandos. Fury informs Rogers that he has the full support of SHIELD.
Within Stark Tower, Hank Pym and Tony Stark argue about how poorly Stark treated Simon Williams. Soon, however, the conversation turns personal, as Pym mentions how he and Stark once worked on together on the project to develop Pym's Ultron robots. Pym discovered that Stark intended to ultimately sell the robots as weapons. Stark defends himself, trying to say that he has changed since then, but Pym remains skeptical.
At AIM headquarters, M.O.D.O.C. and the other AIM scientists begin the Simon Williams experiment. The transformation is interrupted halfway through, however, as Thor and the Wasp break into the facility. During the ensuing battle, the experiment is interrupted and Simon Williams is changed into a being of pure ionic energy. While the Avengers continue to battle AIM and M.O.D.O.C., Williams flies off to seek vengeance on Tony Stark. Eventually M.O.D.O.C. escapes, as the entire AIM headquarters is revealed to be giant aircraft.
Stark and Pym's argument is interrupted by the arrival of Williams. While both try to reason with him, it is clear that he is only interested in destroying Tony Stark. Eventually Simon's ionic structure starts to break down, and he will disappear entirely if not stabilized. Stark rushes the fading Simon to the arc reactor, telling him that it is the only thing that can save him. Ultimately, though, it is too late, as Simon's ionic structure breaks down before he can reach the reactor. Clearly grieved, Stark reveals that he bought Simon's company not to take it over but to insure that the brilliant work that SImon was doing wouldn't be lost if and when the company went under, admitting that he only wanted to work with the fellow inventor.
Late at night, Simon Williams mysteriously reforms in the underground home of the Arc Reactor. Confused on how he is alive again, Amora the Enchantress, along with Baron Zemo and Skurge the Executioner, reveals that it is her magic that brought him back from the dead. She tells him that she has brought him back for one, simple task: destroy the Avengers.
The name of this episode is a reference to Simon Williams canonical codename, Wonder Man. The codename is never otherwise referenced in this episode, but is mentioned later in " Masters of Evil".