Avengers : Season 1, Episode 12: "Gamma World Part One"

“Gammaworld Part One” - A dome of gamma energy envelops the Cube, turning everyone inside of it into a Gamma monster. S.H.I.E.L.D. and Doc Samson know that the Leader and a host of super villains are inside…but worse, the dome is expanding. The Avengers are going in, but they’re not prepared for what they find inside. Meanwhile, Hawkeye catches up to the traitorous Black Widow.