As Fantastic Four: First Steps heads towards its final act, the group is torn between two impossible choices: sacrifice all of Earth to Galactus, or Reed and Sue must give up their child Franklin, who contains the Power Cosmic and enough energy to satiate Galactus' hunger.

Doomsday theory explores how the Fantastic Four might travel to Earth-616. It suggests Reed Richards uses Galactus’ ancient ship tech, combined with his own inventions, to build multiversal transport and rescue Franklin Richards from Doctor Doom’s grasp.