Experiment in Terra

S1, E22: Apollo is recruited by a heavenly being to rescue the mortals on the planet Terra from nuclear destruction at the hands of the evil Eastern Alliance. In "Experiment in Terra," Apollo is captured by a mysterious stranger and enlisted in his angelic mission of mercy to rescue an earth-like planet from annihilation. Accompanied by his celestial guardian, a reluctant and confused Apollo assumes the identity of a soldier from Terra and attempts to warn the mortals of their impending doom. Although Apollo desperately pleads with the leaders of Terra to strive for peace, the young warrior cannot prevent the start of a nuclear holocaust.