WARNING: The following contains spoilers for Immortal Hulk #50, on sale now from Marvel Comics.
The Immortal Hulk series just concluded with the release of its 50th issue. This groundbreaking series revealed that the Hulk's greatest power may be as a result of his gamma-infused body, he cannot die.
But the series tackled so much more. A departure from mainstream superhero topics, it was filled with extreme cases of horror. The comic revealed that gamma radiation was not merely a scientific force, but one with infernal mystical properties that infected every person who had been given gamma-powers, directly connecting them to Hell.
The Immortal Hulk #50 (by Al Ewing, Joe Bennet, Ruy Jose, Belardino Brabo, Paul Mounts, and VC's Cory Petit) is a massive oversized issue that explores different points in time, space, and the cosmic scope of the universe. It opens with a flashback in Ohio, 1901, where two brothers reunite after some time apart. One of them, Samuel Sterns, has a green glowing piece of radium and has discovered a new type of radiation called gamma rays. As Samuel holds the radium aloft, the green glow casts shadows on the wall: Samuel's silhouette is the shape of the Leader, Hulk's greatest enemy, while his brother Rev. Robert Sterns's shadow is shaped like the Hulk.
Details about the brothers' relationship slowly come to light as the final issue continues. Samuel's wife left him, taking their son. In his loneliness, Samuel slept with his brother Robert's wife. After revealing that he is aware of the infidelity, Robert murders Samuel. He also throws out his pregnant wife, unsure if the child is really his. The wife's maiden name is Banner, revealing that she is Bruce Banner's ancestor. This means that the modern-day characters Bruce Banner (AKA Hulk) and Dr. Sam Sterns (AKA Leader) are related.
The rest of the story takes place in the present and follows two of the Hulk's personalities, the green rage-filled persona, and a more practical personality known as Joe Fixit (depicted as the newest incarnation of the Red Hulk). The two have been separated from Banner and are trapped in Hell with a third character, investigative reporter Jackie McGee, who has gamma-powered eyesight.
Traveling through the underworld, the two Hulks encounter physical manifestations of their own Oedipal struggles with father figures, grotesquely hellish body horror, and Kabbalic magic. On top of all this, they must confront the One-Below-All, a version of the devil who is every bit as powerful as the One-Above-All. This gamma-infused Lovecraftian devil looms above, filling the skies of Hell.
In previous issues, The Immortal Hulk explored the various personalities contained within the Hulk and their psychological motives. Bruce developed these personalities to cope with his abusive father. However, both Bruce and his father were poisoned by gamma radiation, which did not merely give Bruce his powers, but corrupted his soul, as gamma connected him to Hell and the One-Below-All. An identity known as the Devil Hulk became the dominant personality, vowing to destroy the world.
On top of the mystical and psychological elements, the series addressed complex social issues. The Hulk's pledge to destroy the world became a rallying cry as people took "the world" to represent everything from predatory social media to late-stage capitalism (both of which he genuinely tried to smash). Since gamma-powered people could not stay dead, the comic was infused with increasingly grotesque scenes of body horror as characters endured monstrous violence.
These elements culminate in the finale, as both Hulks work with Jackie McGee to stop the colossal Hulked-out One-Below-All and free both Sam Sterns and Bruce Banner from the devil's clutches. The green Hulk begins screaming, demanding answers for why the One-Below-All forced Hulk to suffer through so much. Joe Fixit joins the interrogation, saying "you think we don't know whose Hulk you are?" In response, Marvel's uppermost god, the One-Above-All, answers them. This shows that just as god and the devil are counterbalances of one another, the Hulk is also a divine (and unholy) manifestation of this juxtaposition, both savior and destroyer.
The two finally escape with Jackie, saved by the Fantastic Four and Sasquatch, who is now stuck inside the body of Hulk's former therapist, Doc Samson. By this point, Hulk has smashed almost all of his other relationships, with the Avengers now considering him an enemy, and his ex-wife, Betty, once again walking away from him. In the end, Bruce Banner--now reintegrated with the other Hulk personas--slips away alone, free to choose what sort of person he will evolve into at this point.