Scientist Bruce Banner (Eric Bana) has, to put it mildly, anger management issues. His quiet life as a brilliant researcher working with cutting edge genetic technology conceals a nearly forgotten and painful past. His ex-girlfriend and equally brilliant fellow researcher, Betty Ross (Jennifer Connelly), has tired of Bruce's cordoned off emotional terrain and resigns herself to remaining an interested onlooker to his quiet life. Which is exactly where Betty finds herself during one of the early trials in Banner's groundbreaking research. A simple oversight leads to an explosive situation and Bruce makes a split-second decision; his heroic impulse saves a life and leaves him apparently unscathed-his body absorbing a normally deadly dose of gamma radiation.