Three Heroes are caught up in a futile fight against the acid-spewing Corroder, and their only hope is to form a shield, using their energy reserves. But their Hero Cores are nearing depletion, so William Furno decides to jump into action and save his friends.

The evil Meltdown sprays Preston Stormer with a substance that causes him to go insane and threaten his teammates. After he breaks out of the confinements of the Hero Factory, William Furno has to find his leader and save him from himself.

A mysterious black hole opens up above New Stellac City, and the Heroes go to investigate. Upon arrival, not only do almost all the villains show up they've met so far, but their worst enemy, Von Nebula also looms over them.