Astro Boy and Mr. Pompous settle down for a long ride in their train compartment, when suddenly the door bursts open and a strange, dark man, dressed in ancient Egyptian garb, enters. He whispers that he is being followed, then produces an enormous heart-shaped jewel he calls Cleopatra's Heart. He bids Mr. Pompous take the jewel and keep it safe, for it is priceless. It once belonged to Cleopatra herself and was proof that the bearer was indeed Queen of the Nile! Suddenly, the stranger disappears! Afterward, our heroes find that they are being pursued by a gang of dark strangers, also dressed in ancient Egyptian garb! Expert sleuthing by Astro Boy in Egypt reveals that the intent strangers are members of a secret society called the Crimson Brotherhood, whose Grand Master, Rasburton, has created a robot in the image of Cleopatra. Before the multitudes will accept her as Queen of the Nile, though, they demand to see proof of her royal heritage: Cleopatra's Heart. Now Astro Boy realizes ...