We start off with Molecule Man taking Doom back to the beginning of how it all began, the collapse.

MM takes Doom to the Library, originally built by the Beyonders when they thought life was "valuable." Now their experiment is to see what happens if they kill everything at once, but MM has a plan to stop them.

MM is an "infinite being" the same across all realities and part of the grand experiment. MM instructs Doom to keep killing him on realities to start the chain of incursions so that they can defeat the Beyonders. He says Doom has 25 years.

Doom discovers a weakness in the Beyonders, that they are linear and cannot travel in time the way Doom has, his assault on them comes after Thor and the Multiversal Avengers fall, but it leads to the death of those hundreds of thousands of universes.