Susan's cosmic ray irradiated blood cells serve as an obstacle for her in carrying the unborn child to term. Knowing this, Reed, Johnny, and Ben journey into the Negative Zone to acquire the Cosmic Control Rod from Annihilus. Effectively utilizing the device, the baby is safely delivered and is named Franklin, in memory of Susan and Johnny's father. Due to the genetically altered structure of his parents, Franklin is a mutant, possessing vast powers. Seeking to use the boy's talents for his own sadistic purposes, Annihilus triggers a premature full release of Franklin's latent abilities, which were already in the process of gradual emergence. Fearing that his son could release enough psionic energy to eliminate all life on Earth, Reed shuts down Franklin's mind. Angry with Reed for not seeking her input in the matter, Susan leaves the Fantastic Four and has a marital separation from Reed. Medusa of the Inhumans takes her roster spot. With the help of Namor, Susan reconciles with Reed and returns to the Fantastic Four accompanied by Franklin.