Part four in the Star Blazers series, set in 2199 AD and Earth has been threatened with radiation from the Gamilon Bombings. Space Cruiser Argo races against time to find the planet Iscandar and bring back Cosmo-DNA, which can reverse the contamination. The Argo engages in spectacular battles with an enemy fleet commanded by Desslok of Gamilion. On board, officers Derek Wildstar and Mark Venture wage their private war. Chief Mechanic Sandor is revealed to be a cyborg. Captain Avatar, weakened by radiation poisoning, is kept going by the ship's doctor Sane.