Gobo feels as if he's done it all and wishes there was someplace he could explore. But when he hears that the Gorgs are going on a vacation, he thinks his problem is solved, and decides to map the inside of the Gorg's castle. So she gets Boober and Mokey to help scare Gobo, who's got Wembley by his side for the overnight stay. But when the Crown Jewel becomes missing, Junior gets scared and thinks somebody's in the castle. When Gobo and the gang reveal themselves to Junior, Junior later thinks that there's a real thief outside. Junior must work with the Fraggles to catch the jewel thief in order to prove to his parents he's mature enough to watch over the castle.