A Legion team investigates an alarm at their sea-station, which is powered by a pollutant converter. Though they suspect foul play by a half-man/half-fish being, the Devil-Fish knows that aliens are plotting to use the sea-station to poison Earth's atmosphere.; Reinforcements arrive just in time to save Matter-Eater Lad from a firing squad, but the ricochet from the alien ray-guns turns him fat.; Jim Marsh, a classmate of Clark's, is blackmailed into masquerading as Superboy in a neighboring town to help some crooks collect phony charitable donations.; Answering a distress call from Brainiac 5, the Legionnaires are captured by the alien Nardo and taken to the Super-Stalag of Space, where other heroes are also imprisoned. A Durlan who has taken on the form of Superboy, is killed while trying to escape.; After Plant Lad attempts to fight back and is killed by the guards, the Legionnaires plan an escape but Nardo has an informant among the heroes.; Nardo kills Blockade Boy before he can escape. The Legionnaires learn that Weight Wizard has betrayed them, but he escapes them and dies himself.; After Star Boy kills Kenz Nuhor in self-defense, he's put on trial for breaking the Legion code against killing.; Even with Superboy acting as his defense counsel, Star Boy is expelled from the Legion. Dream Girl convinces him to join the Substitute Heroes.; Colossal Boy and Shrinking Violet are stuck on a cruiser with no power, except when Colossal Boy isn't on it.