Reg'lar Fellers Heroic Comics #15

Rainbow Boy joins a dazed Hydroman, after he had struggled with the now imprisoned Helium Gang, and informs him that he has received a strange wireless from the Rock Island Lighthouse. Hydroman investigates, making his way into the lighthouse and finding the keeper, who alerts Hydroman that a gang of smugglers are attempting to bring in diamonds from South America. While the keeper alerts the authorities, Hydroman rounds up the crooks and turns them over to the Coast Guard.