"Breakout" is the name of the first two episodes of the animated television series The Avengers: Earth's Mightiest Heroes. It was originally broadcast on Disney XD in the United States on October 20, 2010. Its broadcast was preceded by the release of a 20-episode online "micro-series" which introduced the individual heroes and set up the plot.
Plot
Part 1
After Iron Man stops an arms trade between A.I.M. and Lucia von Bardas, he transports them to the Vault and returns to New York. In the Cube, Samson passes by the jails of Wrecker, Zzzax and Absorbing Man. Samson arrives in the holding cell of the Hulk who is in his pre-transformed state, Banner warns him that S.H.I.E.L.D. are going to use the villains as weapons. Samson tries to calm Banner, but he insists that the cube is dangerous. Thor watches over a city when he gets approached by Balder the Brave from Asgard. Balder tells Thor that his father before entering the Odin Sleep asked Thor to come back and protect Asgard. Thor rejects the offer, Balder doesn't understand and asks why he is so occupied to the city. Thor tells him that he is needed here so that he can make a difference unlike in Asgard who only solely relies on fighting. Below them, Jane Foster is taking care of some people who were involved in a traffic accident, while a speeding car bounces from the ground and is going straight to Jane but is deflected by Thor. Jane thanks Thor for saving her and is wondering if he is following her, Thor tells that he is intrigued by her since she doesn't seem to be scared even though she is a mortal. Meanwhile, Hank Pym talks with Mad Thinker to see what he meant when he referred to the villains in the super prisons as "soon being free". Also on board, Wasp declines Maria Hill's invitation to join S.H.I.E.L.D.
Bruce Banner warns Leonard Samson about SHIELD's ulterior motives for keeping him imprisoned. Meanwhile, Hawkeye sits silently in his cell at the Vault, after being framed by the double agent, Black Widow. Just then, all four super prisons' security systems shut down, allowing the combined 74 supervillains to escape. The tech-based foes in the Vault raided the armory getting their weapons until they are stopped by Hawkeye. Iron Man is alerted and immediately returns to the Vault. Iron Man is outnumbered by old enemies at the Vault. To keep the villains from escaping, Tony self-destructs the Vault. The radiation-based villains of the Cube break loose, during which Samson is exposed to Gamma radiation when he is injured by Zzzax. Bruce transforms into the Hulk and escapes with Samson, heading for the nearest civilized area. The villains try to follow him, but the Leader orders them to remain. The prisoners of the Pym-particle shrunken Big House are freed and the prison itself grows back to normal size causing the Helicarrier it was kept in to crash into the Hudson River. Nick Fury learns of the other prisons' situations and realizes the same must be happening at the secret fourth prison, the Raft. It is at this moment, Graviton awakens. He lifts the prison into the sky, and confronts Fury, who now sees him as another supervillain, calling him "Graviton".
Part 2
A flashback from 10 years ago reveals that Franklin Hall (Graviton) joined S.H.I.E.L.D, and was tasked by Nick Fury to recreate the "Super Soldier serum". However, the experimental reactor was pushed by Hall to critical levels and Fury ordered him to shut it down. Hall refused and was nearly killed when the reactor blew. Afterwards, he discovered while in recovery that he developed superpowers from the accident, unlimited levels of gravitational manipulation. Blaming Fury for the accident, Hall prepares to escape and wreak retribution on Fury. But SHIELD doses the room with gas, leaving Hall unconscious. He's then placed in high-level security within the underwater prison, the "Raft".