While the Avengers are investigating one of Baron Helmut Zemo's possible hideout somewhere in South America, Hawkeye is left to defend Avengers Tower from Baron Helmut Zemo who has taken the Masters of Evil members Beetle, Fixer, Goliath, Moonstone, and Screaming Mimi under his leadership.
Appearing in "Under Siege"
- Captain America (Steve Rogers)
- Iron Man (Tony Stark)
- Black Widow (Natasha Romanoff)
- Falcon (Sam Wilson)
- Hulk (Bruce Banner)
- Hawkeye (Clint Barton)
- Masters of Evil
- Baron Helmut Zemo (Joins team)
- Moonstone (Karla Sofen) (First appearance)
- Fixer (Paul Ebersol) (First appearance)
- Beetle (Abner Jenkins)
- Screaming Mimi (Melissa Gold)
- Goliath (Erik Josten)
- Hydra (Mentioned)
- Circus of Crime (Mentioned)
- Throughout the episode, Hawkeye is barefoot.