United We Stand continues directly from Divided We Fall, showing how the protagonists of all Ultimate books try to bring the U.S. back together.
Kitty and her team of X-Men try to motivate the traumatised mutants who escaped from a camp to fight against the sentinels and not fall back into passivism. They then start liberating other mutant camps declaring their mission to make mutants free people again. They fight the sentinels and reuse the old camps for new buildings. Kitty meets with Captain America who makes her an offer that shocks her: the mutants can either live in separate parts of the country, isolated from the rest of America or they can take a serum to lose their mutant abilities. Cap does not believe that people would accept integrated mutants although he would prefer that.
Captain America and the Ultimates fight against drones who kill refugees, initiated by the mysterious Morez. They rescue the refugees and through the broadcast of their actions, Cap gets elected as the new President of the U.S.A., somewhat surprisingly. He accepts the election and in one day solves the crises between North and South Carolina, Detroit and an attempt to kill him. Meanwhile, Thor faces the one who is pulling the strings in all the disasters happening in the U.S., Modi, his son. He works together with Hydra to destroy America. He brings down the Ultimates with the Mind Gem, forcing them to fight each other.