Yberra, a notorious international jewel thief, and his gang show up in New York at the same time a famous jewelry shop is to open with a public display of some of the world's richest gems. Robin Scott thinks it may be merely an interesting coincidence--until an investigator is killed practically at his feet. Robin then takes on the job of protecting the insured gems. The display ends without mishap, and all dangers seem ended. But when a gunman trails him and Phyllis through Central Park and attempts to kill him, Robin is certain that Yberra still plans to steal the fabulous gems. Robin makes plans of his own, and in a surprising and thrilling climax he captures the entire gang.