Rather than turning Magneto over to the authorities and virtually ensuring the death penalty for him, Professor X secretly brainwashed his old friend and tried to rehabilitate him.
Fury and his Ultimates track down the Xavier Mansion, whose location was hitherto unknown, and find it empty, the X-Men having relocated.
In preparing to battle the X-Men, Captain America reveals he knows more about Wolverine; they fought together in World War II, when Logan went under the name James "Lucky Jim" Howlett.
Magneto anticipates Xavier's double-cross, tracks down the X-Men's new base in turn, and anonymously tips off their whereabouts to the Ultimates.
All of the X-Men escape except Charles Xavier, who stays behind to delay the Ultimates and is captured by Nick Fury.