Our mice arrive in the beautiful city of Bangkok, "The Venice of the East", just in time to witness the coronation of Crown Prince Vajiravudh. Their cousin Prem explains that when the prince becomes king he will be able to wear the priceless Star of Siam, a sapphire ring that sparkles in the sunlight. Unfortunately, Notail Nogoodnik has his heart set on stealing the priceless jewel. When the Prince stops his royal procession to let his elephant, Peanuts, have a drink of water, Notail sneaks off, clutching the ring in his greedy paws. The prince instantly accuses Prem's friend Trang , who was the only one left alone with Peanuts of stealing the ring. It is up to Emily, Alexander and Prem, with some help from Trang's wise old elephant Chai-chai, to find Notail, get back the Star of Siam and slip it into the Prince's pocket. When the prince discovers it safe and sound, he apologizes to Trang and lets Chai-Chai carry the new king in the royal procession!