Did you know that there's a theory that the bacteria in our bodies actually controls our moods and may even be responsible for elements of our personalities? TONY STARK and BRUCE BANNER did. - What happens when a 20 million-year-old evolutionary catalyst infects a HULK? Could it be a cure? - Meanwhile, on the outside, CAPTAINS MARVEL AND AMERICA must find the missing scientist before he unleashes said bacteria on the world.