Badou thinks there's an intruder in the palace and created a series of traps to catch him. Could the intruder be someone very small or someone as big as Badou thinks of in his imagination?
Badou his room playing with Chiku imagining looking for the Gold Mine of Gaxx in which she thought was a myth. As Badou continues to play Chiku throws one of the pillows and Badou deflects it causing it to hit his grandfather. Known that they were pretending he told them to get their so-called enemy, he asked if Babar was surprised and he said, "I was but I tried to get the facts first." Then all of a sudden Cornelius yells from the map room, saying that one of the maps went missing.
So Babar advised him to settle the matter quietly without knowing Badou and his friends were thinking of the same thing. Badou and friends were discussing about what they were going to do at Gallop's Grotto including (Munroe and Zawadi), back at the palace everyone's wearing disguises to look out for the theft. At first, they begin to suspect the ambassador while Cornelius set the trap just as he was opening the door he assumed that were everywhere. Thinking that they received the map but it was just a sandwich, when they took a look at the photo that was left in the throne room. To their surprise as much as Badou's horror the spy turned out to be a mouse, Chiku explained that both mice and elephants don't get along.
Back at the Grotto the kids discussed what they were going to do, Badou letting his fear get the best of him thinking that this one mouse is planning an invasion and work out a new plan. Back in the map room, Cornelius thinking he knows what the theft(s) looks like is ready for them. So he patrols the palace at the same time as Badou and the others put their plan into action setting the trap with glow in the dark paint balloons and getting into their hiding spots when someone was coming, but the person turned out Cornelius. Then everyone sprang into action thinking they caught the spy, but made a whole bunch of ruckus and ensnared themselves their own trap, right after that the mouse came in but Badou was too scared to do anything.
After that Babar released everyone and just before the thief left, Badou and Babar followed the mouse's footprints all the way down to the cellar. To their discovery the mouse was named Deb Mouse and the king was happy to meet them, to Badou's surprise he told his grandfather that they were planning an invasion, but it turned out she needed paper to make a new nest since their old one got flooded. So Badou realized his mistake and apologize to them about not getting the fact straight first, and the king gave them a new place to stay in the throne room as protectors of the palace's maps. To celebrate the young prince decided to have a group picture taken as a sign of friendship.