A sinister oriental and his gang blow up a dam to hurt America's prosperity.; Back in the ship, the boys bring Elmer with them back to Earth, but the Professor is still on Mars.; Hop learns that Gerry is a girl just before she is kidnapped, and he goes after her in the roadable autogyro.; Scribbly applies to a newspaper as a copy boy for $10 an hour, but is almost hired as a cartoonist for $100 a week. Still, another newspaper hires him as a cartoonist, but Scribbly's family doesn't believe he was hired until his cartoon strip, "Why Big Brudders Leave Home," appears in the daily newspaper.; Karl McReady, now known as Popsicle Pete, visits New York as part of his contest winnings.