Mephisto decides that he must take action and destroy the Beyonder--he can't take the risk of the Beyonder killing Death (or worse) again. Mephisto has collected the remnants of all the energy that the Beyonder used to kill Death, and built a machine, Beyondersbane, that will use that energy to kill the Beyonder.
The Beyonder, ignoring all this, has situated himself on a Pacific island to think over his plans and existence. Ed Strunk, who lives on a neighboring island, comes over to visit. The Beyonder tells him his story, and Strunk (a fairly loud, boorish character) is tantalized by the idea of simply sitting and thinking. He eventually returns with more people who want to all sit with the Beyonder and take part in his "think system."
The Thing also happens to be in the Pacific, shooting an action movie. Hopper Hertneky, a pilot and friend stops by to see him. The conversation steers towards the Beyonder, whom Ben Grimm hates with his whole heart, partly for the ordeal of the original Secret Wars, which in Grimm's mind led to the loss of his girlfriend to Johnny Storm, and partly for a tense wrestling match in which the Beyonder brought Grimm to the point of almost killing him.
Meanwhile, Mephisto is putting his plan into action. He sends a subordinate, Bitterhorn, out to 99 villains. To each one, he promises a great reward if he helps kill the Beyonder. The villains include the Juggernaut, Electro, Baron Mordo, the Abomination, the Rhino, Emma Frost, Dr. Octopus, Kraven, Silver Samurai, the Vulture, Dr. Doom, the Wizard, Hobgoblin, the Absorbing Man, the Mole Man, Anaconda, the Wrecker, Titania, Diablo, Kang, Ultron, Blastaar, the Living Laser, the Enchantress, the Executioner, the Crimson Dynamo, the Grim Reaper, the Blob, and M.O.D.O.K., among others (the last 6 are only evident from the cover).
However, the villains do not realize Mephisto's full plan. He has put a mystic seal on all of them, so that if any of them touch the Beyonder, or if he uses his power to stop any of them, it will trigger the Beyondersbane weapon, killing the Beyonder, the villains, and a third of the universe. In fact, Beyondersbane is not only powered by the Beyonder's own expended energy, but also by all the power in our own universe, courtesy of a consensus of the cosmic entities, who are now arrayed against the Beyonder. Eternity himself will act as the gunner for the weapon, even though the use of the weapon will destroy a third of himself.
The Beyonder's "think system" has become a worldwide phenomenon, and people are streaming to the island to participate. The Molecule Man hears about it through the TV while playing Trivial Pursuit with friends. He goes off into his room and checks around the universe, and figures out the cosmic entities' plan, but because they're being careful, the Beyonder won't notice himself unless Owie tells him. He doesn't know what to do; he's becoming afraid of the Beyonder's careless whims and extravagances, but he is also his friend.
The Thing also hears about the Beyonder, and can't believe he is so close. He becomes more frustrated.
Mephisto has finally put together his entire Legion Accursed, and is ready to strike. If he doesn't do it soon, the machine will melt down due to the intensity of the Beyonder's stored-up power. However, the Beyonder is getting annoyed with all the people coming to his island, and starts thinking about moving somewhere else. Mephisto must come up with a plan to keep him in place.
He appears to the Thing at night, seemingly in a dream, and convinces Grimm to sign a contract, giving away his soul in return for a hundredfold increase in his power. The Thing swims towards the Beyonder's island. Crashing through the landscape, he tells the Beyonder that he has come to kill him. But the newly-meditative Beyonder refuses to fight. Ed Strunk tries to mediate, when suddenly the Legion Accursed is released. They storm toward the Beyonder, and the Thing has the same dilemma as Reece did earlier: does he stop them, or does he want them to succeed? Reece continues to stay passive, but the Thing vaults into action, fighting the villains back. With his vast increase in power, he makes mincemeat of the villains. Mephisto can't let this happen, so he tears up the Thing's contract, thereby taking away his extra power. Only one villain remains: the unstoppable Juggernaut.
The Juggernaut knocks the Thing aside easily and moves toward the Beyonder, who has yet to lift a finger in his own defense. However, summoning up his remaining fighting spirit, the Thing grabs the Juggernaut and stops his forward motion before he can touch the Beyonder.
The critical point has passed: Beyondersbane melts down and the Legion Accursed disappears. Reece sees that the danger is gone, but is fearful that soon he will no longer be able to sit idly by in the midst of others' machinations. The Beyonder, however, is cheerful: perhaps his true role in life is helping others realize their role, as he did when he passively helped the Thing realize that he is a hero, not a murderer.
The story continues in New Mutants #36, Amazing Spider-Man #273, Uncanny X-Men #202, Defenders #152, and Spectacular Spider-Man #111.