The Fantastic Four and the military are shocked when in attempting to change the Hulk back into Bruce Banner, the Thing freed the Hulk and decided that he would team up with the Hulk due to the inhuman treatment the green goliath had received from the military. When the FF and the military try to stop the two man-monsters from escaping, they easily smash through them.
Breaking into the hangar, Hulk and the Thing smash all the planes except for the one in which they escape. While in the air, the Thing suggests that they head back to the desert where the Hulk usually hangs out and asks him where they should go. Hulk dimly recalls a rock formation that he can sit on and think. As they fly by the Gateway Arch in St. Louis Missouri, the Hulk confuses it for his favorite sitting spot and demands that the Thing bring him there. Ben experiences a momentary dizziness and agrees to take them down.
With Colonel Sellers about to attack, Mr. Fantastic manages to convince him to let the Fantastic Four go out and try to capture the Hulk and their errant teammate first. The four leave in another ship, and when they are in the air, Reed tells the others that Thing's constant proximity to the Hulk for an extended period of time may have an effect on him due to the Hulk's gamma radiation and stresses that they need to get to Ben before it's too late.
They end up in St. Louis, where they spot the Hulk and Ben on a rooftop. The Hulk is furious that they didn't land directly on the Gateway Arch (being unable to safely land on it escapes the Hulk's understanding). When the Hulk is about to toss a chunk of concrete on the soldiers that have gathered below, the Thing realizes the folly of allying with the Hulk and smashes the chunk of concrete before the Hulk can throw it. Not understanding what happened, the Hulk jumps down to attack the soldiers directly. Ben decides to try to go down and stop the Hulk when he is struck by yet another dizzy spell. Before anything can happen, the Hulk is distracted by Reed Richards, who orders the Hulk to stand down and allow them to take him into custody. He explains the danger Ben faces being in prolonged proximity to the Hulk; this angers the Hulk, who attacks them for trying to separate him from his new friend.
A battle ensues, with the Thing and Hulk against the remaining members of the Fantastic Four. The Human Torch tackles the Thing, who easily knocks out his young comrade, sending him flying into Reed. With Reed stunned on the Gateway Arch, he is an easy target for the Hulk, but he is saved from a thrashing by Sue's invisible force field. Realizing the mistake he has made, Ben begins fighting the Hulk. During their battle, he suddently realizes he's changing back into Ben Grimm. He is easily knocked off the Arch and sent falling to the ground. Now completely in human form, Ben falls to a certain death but is saved by the Human Torch.