Furious at Tony Stark for buying up his company, Simon Williams seeks revenge by undergoing a dangerous AIM procedure, overseen by MODOC and the Grim Reaper (Williams' brother), which turns him into a being of pure ion energy.

When The Leader creates a bubble of gamma radiation emanating from the Cube that mutates any human it touches, the Avengers team up with Doc Sampson to stop him. Meanwhile, Hawkeye infiltrates a Hydra base in order to capture Black Widow.