Ling Ling's estranged sister, Lang Lang, shows up at the Narutaki Detective agency unexpectedly. Six months prior, she had joined with Narutaki's rival, Le Bled, and ran away with him. Now, Le Bled has come for a showdown with Narutaki, and Lang Lang's visit is part of his plan. Lang Lang gasses Ling Ling and disguises herself as her sister, then tries to poison Narutaki. He, of course, is too smart for all that. When the plan is foiled, Le Bled appears, and tells Narutaki the only way to save Ling Ling is to defeat him in battle. The fight is joined, and Narutaki does save Ling Ling, but in doing so, Lang Lang and Le Bled are able to escape.

A major convention of world-renowned scientists is coming to Steam City, but there is a problem- someone has been kidnapping the attendees. Narutaki narrows down the list of potential targets to the next two, and goes to warn them. Later, one of them is indeed snatched, but Narutaki and Goriki foil the attempt. Later, at the convention, it is revealed that the other, Dr. Gerhalt Von Halt, is the one behind the kidnappings. He wants the knowledge of the scientists to make his megamaton better than human. He claims his evil identity- Dr. Guilty- and tries to capture the remaining scientists. Narutaki is having none of it, however, and the battle is on. Dr. Guilty's megamaton is strong, however, and Goriki is badly damaged. Just when it seems as though the heroes will be defeated, the scientist Narutaki saved earlier gives Narutaki special bullets; with which the bad guys are at last defeated.

The Crimson Scorpion is on a thieving rampage! She is using disguises fluidly and stealing all sorts of jewelry, but she keeps being disrupted by Narutaki and she ends up getting away with nothing. However, the Crimson Scorpion has set her sights on the most important piece of the Kebecks Royal Jewels – the Blue Teardrop. This necklace is worn around the neck of the reigning female royalty, and the Royal Princess of Kebecks is going to be wearing it during a ceremony when her engagement to the Steam City Prince is announced. Can Narutaki stop this criminal from stealing this important piece of jewelry?

There's a festival approaching to celebrate the dragon guardians of Steam City, but to everyone's surprise, a real dragon shows up and begins breaking into the local jewelry stores. At least, it seems to be a real dragon. The shop owners are living in a state of perpetual terror, and it seems that only Narutaki will be able to crack the case.