The X-Men discover their home completely destroyed and set out to search for the person (or mutant) responsible for the attack. They encounter two suspects--Colossus, a Russian immigrant who is helping construction workers; and Juggernaut, a titanic super-powered villain committing crimes in the city in order to lure Professor X out of hiding. It is revealed that Juggernaut is Professor X's half-brother and is harboring resentment toward his more accomplished sibling.