Ensai, a traveling monk, buys a Japanese man, Osumi, who is being sold as a slave at a market. He tries to set Osumi free, but the freedman is interested in what Ensai is doing. Ensai tells him he plans to collect Buddha's relics and bring them to Kotan. He also plans to erect a new temple in Japan with the relics. Ensai crosses the desert with a caravan, and Osumi tags along, helping the monk when he collapses in the desert. Due to a misunderstanding, Ensai thinks Osumi is "Really", because to every statement the monk makes during the journey the freedman only says "Really?". The caravan is attacked by bandits, and Osumi and Ensai take refuge in the side of a mountain, which happens to be the place where some of Buddha's relics were kept. In the morning they collect the relics, but find everyone else has left. While continuing to cross the desert, they see two women running by, one more richly dressed than the other. They come to a pond where they meet an old wizard. The wizard asks if they have seen two women go by and Ensai says yes.Osumi and Ensai reach the town of Pesil, but all of the residents are scared of them. A small group of people are willing to accommodate them. A procession of guards marches down the street. Osumi stays outside to watch and sees the two women from before in a cage. The more richly dressed one discreetly drops Osumi a pink piece of fabric. He learns that the woman who dropped him this piece of fabric is the queen, and that the king is suspicious of everyone. What nobody knows, however, is that the leader of the bandits who attacked the caravan earlier is living in the castle, and the Chamberlain plans to overthrow the king and make his daughter Spuria the queen. Suddenly the group is ambushed, and everyone except Osumi is arrested. Osumi goes to a pond, and is joined by another man. Osumi thinks the pond look suspicious. The man recognizes it as the Hell Pond. The two are accosted by a witch, who announces herself as the guardian of the pond, and reveals the man to be the Captain of the Guards. She attacks the Captain, who has climbed up a tree, but is stopped by the wizard. The wizard tells Osumi and the Captain that the Hell Pond is irrigated to the moat of Kigan Castle. Osumi sneaks into the castle, and presses the queen for questions on where his friends are being kept. The queen urges Osumi to run away, but Osumi is determined to confront the king. A chase ensues, and Osumi breaks into the king's chamber, using Spuria as a human shield. He asks the king why he mistrusts his own people, but the king sentences Osumi to burn at the stake the next day. The king's advisors, who are working with the Chamberlain and the bandit leader, are also allied with the witch. They worry about Osumi exposing their traitorous plot. The witch decides to destroy Osumi in the Hell Pond. Disguised as the queen, she sneaks into the dungeon under the cover of night. She sees Osumi sitting in his cell, shackled in chains and sleeping tight. She tries waking him up, but nothing she says or does is able to rouse him from his slumber. She then hears the voice of the wizard, and reveals her true form. She suspects that the wizard put Osumi under a sleeping spell. The wizard flatters the witch by telling her how she looks in her queen disguise and asks her to change into it once again. She starts to do so, but the wizard disappears and a guard comes. The witch, stuck in an awkward position, also vanishes.The next morning, Osumi is taken to be executed, and Ensai pleads to speak to the king with him. Spuria takes them to the Chamberlain. Ensai asks the Chamberlain to allow Osumi three days to deliver the relics to Kotan, and offers himself to take his place. The Chamberlain allows for this.Osumi travels the desert to Xi'an and gives the relics to his brother. On his way back to Pesil, he is attacked by bandits and is thrown into Hell Valley. The witch traps him down there with a wall of flames. Osumi survives. The wizard looks after him overnight.Later in the morning, a dehydrated and exhausted Osumi makes his way back across the desert. He doesn't make it to the stake in time but Ensai hasn't been executed yet. Slowly but surely he makes his way to the stake and cuts Ensai's bonds, allowing himself to be bound instead. The king is awed by Osumi's selflessness and sets him free.The Chamberlain takes control of the castle by force and has the guards attack the town. The bandit leader kills him and takes control. A battle ensues. Osumi fights the bandit leader on the portcullis and causes him to be impaled by his own spear. The witch tries to burn the castle with the moat, but two servants raise the drawbridge. With her foot still on the pedal she learns too late that the wizard replaced the burning water with regular water. She falls into the moat and evaporates.The next day, the king wants to reward Osumi and Ensai, but they continue to travel along the silk road.