The Avengers are trapped inside the Vault, a maximum-security prison built to house super villains. Now they must battle a cadre of the Marvel U’s deadliest villains including Radioactive Man, Klaw, Rhino, and Spider-Man’s arch nemesis, Venom! To make matters worse, Freedom Force, the former Brotherhood of Evil Mutants now a government sponsored strike force, are on the scene to complicate things. Can Earth’s Mightiest Heroes quell a superhuman prison break when they’re not sure who they can trust?