After leaving China under the threat of Zares, our heroes finally arrive in Japan. They must absolutely find there the third City of Gold against which the infamous Zarès promises to release Athanaos, the father of Esteban.

The one who attacks Esteban, Tao and Zia is Yoshi, an old man who keeps fiercely the impressive Orichalcum sphere. Yoshi reveals to the children that it is a utsuro bune, a sacred object, rejected by the sea thousands of years ago and revered since as a gift of the gods.

Near the temple of Izumo, the children succeed in extracting Esteban from the water, but attract the attention of one of the guards who go after them. Within the walls of the temple, our heroes finally see the mirror shield out for the parade, but an earthquake creates panic!

Inside the temple, the shield-mirror leaves the children perplexed: according to the silhouette in the utsuro bune, it is the path and the key to the next golden city. They realize then that the ornaments of the mirror represent a volcano, off Kagoshima. Will the city be underneath?

At night, as Ichiro goes to take his guard duty at the castle, Esteban follows him and tries to convince him to help him to escape Mendoza and his men. Ichiro refuses, reminding Esteban how his presence and those of his friends already endangers his whole family.

Mendoza and his men takes control of the nave and makes the prisoners Gaspard and Ambrosius. They spot the Condor and rediscover the children who introduce Yoshi and his family.

Mendoza narrowly escapes the attack of Ambrosius. The latter claims that it was Mendoza who assaulted him, but he loses his compass, which Esteban picks up and tends to him by reflex.

In the center of the cave, at the top of a pyramid, our heroes discover a sphere of orichalque floating on a lake. Attacked by thousands of giant crabs, they manage to take refuge inside.

In the treasure chamber of the Golden City, the crowns found by our heroes allow the wearer to control the orichalc cubes by thought. As he goes to look for Tao in the Thallios to show him their discovery, Estéban passes by the statue: he seizes the crystal pearl.

Zarès managed to escape with the crown and the crystal pearl. Aboard the Condor, Esteban explains his plan to his friends. He arranged for Zarès to take the crystal pearl that had guided the Thallios to the golden city.

The mysterious pursuers turn out to be children whose parents were abducted by the men of Ambrosius to work forcibly at the Fort of Pattala. When they learn that our heroes are not friends of Ambrosius and that Esteban's father is also a prisoner, they decide to unite their strength to deliver them all.

At the fort of Pattala, Esteban was spotted by Ambrosius. When escaping, he sees his father in a cell but must flee because he is persecuted by Laguerra, the right arm of Ambrosius, and the guards of the palace.

Tao is now in the hands of Ambrosius. The latter tries to return to his good graces, but Tao sees him as a traitor and refuses to give him his confidence. However, Tao discovers the laboratory of Ambrosius and is impressed by all that it reveals to him.

According to the plans of Ambrosius, Laguerra and the soldiers find only a deserted village. Laguerra spotted the children hidden in the trees. She hesitates, but does not denounce them and leaves without saying anything with her men in direction of the fort.

While in the village, the children try to repair the Condor, Pichu sent by Tao finds them and deliver them a message from Atanaos. He reveals that the Rajah was drugged by Ambrosius.

The fort is taken by assault from all sides: the villagers, Tao and Atanaos are freed. Esteban manages to inject the antidote to the Raja who regains his spirits and realizes the betrayal of Ambrosius. To escape the soldiers of the Rajah, Ambrosius uses the black suns that trigger a fire in the fort.

Esteban spends his own time with his father Athanaos finally found. This one reveals to him well to know Ambrosius, to have been his friend when they were young. For their part, Zia and Tao discover in the Memory Temple a key clue in the search for the fourth golden city.

Our heroes are surrounded by a troop of Bedouins. Their intrigued chief observed the medallion and then returned it to Zia apologizing for the young thief: a Bedouin never flies. When the children leave, he asks the young boy to follow them to find out what they are doing in Ormuz.

On board the condor, Esteban is worried about what happened to Mendoza and his men, but his friends remind him that Mendoza is resourceful and their priority is to prevent Ambrosius from appropriating the muen knowledge and make it Weapons of war like the black suns.

The children finally managed to penetrate inside the ziggurat. They start their descent in search of the sacred sails of Princess Rana'Ori in the bowels of the pyramid, where, according to the inscription discovered in India, they should be found.

Zarès aided by Laguerra captures the children and pushes them towards the exit, revealing to them that he possesses, anyway, another track towards the fourth city of gold. They just need them and their medallions to open it.

In the desert, the suspected noises heard are produced by none other than Sancho and Pedro lost in the dunes. They finally found their friend Mendoza. In Manfuha, the children try to leave the oasis to reach the Condor, but the compass they steal from Zarès detects something.

The children reach Condor thanks to Laguerra who confronts the soldiers alone at the risk of his life. Despite the reluctance of Tao, our heroes return to collect it and make it climb aboard. Under the fire of the defensive guns of the fort, they managed with the Condor to recover the box containing the sails.

The Bedouin chief presents to the children the second veil they were looking for, transmitted from generation to generation by the Chaldis tribe. They try to read a plan to the city of gold, but the sails do not reveal anything.

On board the nave, Laguerra prevented Gaspard from killing Mendoza, arguing that Mendoza would be more useful to their living plan than dead. The children enter the city in search of the tomb of Princess Rana'Ori, but the sumptuous city seems deserted.