Dr.Scarabeus was a biologist in Cairo. He developed a way to create clones, splitting and melding cells from humans with animals to create "Anti-Men", but many people were horrified by the ethics of his concept, his wife included. Feeling that his detractors were afraid of his genius, Dr.Scarabeus took his daughter and travelled to the Pacific, setting up a base on an island hundreds of miles from anywhere. There he continued his experiments, at first creating monstrosities which he locked away, before finally succeeding in creating two successes, Felix, a cat-man, and Fangor, a wolf-man. Dreaming of returning to the world at the head of an army of Anti-Men who would pound his enemies' cities flat, he decided that now he had perfected the method, he needed to create more powerful Anti-Men. Hearing of the Hulk, he felt that if he could possess the giant creature, then he would be unstoppable. With this in mind, he sent Felix and Fangor to America to hunt down the beast.
Dr.Scarabeus greets his returning minions when their helicopter lands. They inform him that their mission was a success, that the plan worked. Arrogantly the Doctor points out that it was his plan, so of course it worked. Now with the Hulk in his power, he reasons that nothing can stop him. Only seconds later the angry giant smashes his way out of the titanium cell he has been imprisoned in.
As the Hulk proceeds to demolish the helicopter, Dr.Scarabeus sends Felix to sound the alarm. The he tries to contain the Hulk with a whip, only to have the Hulk respond by ripping a metal strut off the flying machine and swing it at him. Scarabeus dodges just in time, and is granted a brief respite by the arrival of several of his men. They attack the Hulk with electric goads. In return the Hulk throws the entire helicopter in their direction, before using the confusion that creates to rush off into the nearby jungle. Scarabeus tells the incredulous Fangor that they have brought the most powerful creature on Earth to the island, one who will be the key to the scientist completing his work. He tells his wolf-man to detail someone to clear the wreckage away, stating that with no way to escape the island, the Hulk will be caught soon enough.
The mad doctor enters the main building of his scientific complex, where he is greeted by Felix and his daughter Tisha, who came running when she heard the alarms. He tells her it is nothing to worry about, then orders Felix to be ready to leave in five minutes. Then he stalks off to the armoury. He is getting a rifle when Tisha catches up with him, and tries to talk him out of the insane path he is travelling down. He rebuffs her reasoning, telling her she is just like all the others. Armed with netting and rifle, and accompanied by his two Anti-Men, he sets off on the hunt.
Pursuing in one-man gyrocopters, the three hunters soon locate the green giant, who starts throwing rocks at them. Trying to get the Hulk to stop doing so, Dr.Scarabeus opens fire with his tranquilliser gun. The Hulk flees, climbing up a cliff face at the jungle's edge. Unable to safely reach him, Scarabeus orders his minions to land, so that they can pick up the pursuit on foot.
A little while later Felix spots a man moving through the jungle, and holding him at gun-point calls his master. Scarabeus demands to know how the man came to be on his island, and their captive states he is Banner, a marine scientist who was shipwrecked a few days earlier. Unsure whether or not Banner is telling the truth, Scarabeus orders Felix to take Banner back to the base while he and Fangor continue the hunt, little realising that Banner is actually the Hulk's alter ego.
Shortly afterwards Scarabeus and Fangor return to base too, where the scientist discovers his daughter Tisha with Banner, and finds that she has told the visitor all about his work. Feeling Banner now knows too much, Scarabeus tries to shoot him, but the fleet-footed captive darts off down a corridor and vanishes round a bend. Hot in pursuit, Scarabeus and Fangor are shocked when they round the corner to find the Hulk waiting for them. Fangor turns and flees, leaving his master to face the raging beast alone.
Scarabeus calls out for the fleeing Fangor to help him, but then the Hulk snatches the gun out the doctor's hands and breaks it into scrap. Fangor calls out to the doctor that there is no way they can stop the Hulk, but Scarabeus disagrees, and runs the door to Gograth's cell. Seeing this, Tisha shouts to him that he can't do this. Scarabeus strikes her for arguing with him, and then they watch as the Hulk comes stomping round the corner straight into the arms of Dr.Scarabeus' most monstrous creation. Then he and Fangor retreat. leaving the two giants to battle it out. Much to the scientist's surprise a few minutes later the Hulk emerges victorious and smashes his way through a wall and back into the jungle, accompanied by Tisha. Scarabeus orders his minions to fetch the electric goads so they can return Gograth to his prison; after this he will see to the Hulk and his treacherous daughter.
Scarabeus oversees the return of Gograth to his cell. Fangor informs him that all the First Ones seem particularly rebellious today, but Scarabeus is unconcerned. He states that once he can use the Hulk's cells to create new supersoldiers he will no longer have time to waste on his manimals. Felix asks him what will happen to them at that point, and is told that they will get their rewards, but they won't be needed any more. Then a guard rushes in to tell the Doctor that the Hulk is back, smashing his way in through the perimeter. Arming himself with another gun, Scarabeus heads his forces in confronting the brute, and tries to hit him with anaesthetic darts again. This time the Hulk is ready though, and blocks the doctor's shots with a downed tree, which he then throws at Scarbeus. The doctor orders his men to move in with the goads, but the Hulk bound past them into the building, with Scarabeus and company giving chase.
They enter the building to discover the Hulk has freed all the First Ones and is leading them in destroying the facility. Scarabeus cries for them to stop, but Fangor and Felix recognise the better part of valour, and haul the doctor bodily out the building. With the First One right behind them, the doctor orders his two loyal Anti-Men to use their rifles, but this is the last straw for his harassed minions; they will not fire on their own kind. They abandon Scarabeus, who flees into the jungle. As he tries to cross a river using a fallen tree as a bridge, he encounters his daughter Tisha, who demands to know what is happening. Standing on the log, he struggles to break free of her grasp, screaming at her that she knows he cannot swim, and that she must get out the way as the Hulk is after him. Sure enough, the green goliath enters the clearing just as Scarabeus knocks his daughter clear of him. The Hulk stamps on one end of the tree trunk, catapulting Scarabeus into the air and down into the Hulk's arms. Having heard Scarabeus say he can't swim, the Hulk takes him over to a smaller adjacent island, bereft of any civilisation, and maroons him there.