 After investigating it, they are welcomed by an alien race known as the Mercora, who had fled their own planet which was destroyed and intend on making Earth their new home.However, they are at war with the Nesk, and do not have the technology to help the Animorphs return to their own time.The Nesk, however, do—so the Animorphs storm the Nesk's camp in order to steal a warhead to recreate the explosion that sent them into the past.