In 13th century Tangiers, master thief Yussef, hired by Emir Mokar, an agent of the city's regent Prince Mustapha, is sent to kill baby prince Hussein so Mustapha can claim the throne in Hussein's stead. Yussef cannot go through with it, so instead he decides to raise the child as his own and names him Julna. The only proof of Julna's true identity is a tattoo of the royal seal on his arm, which Yussef keeps hidden under a silver armband.
Eighteen years later, having grown to manhood and the arts of thievery, Julna infiltrates Mustapha's palace to raid the treasury, but is thwarted by the room's tightly barred sole window. While evading the guards, he catches a glimpse of Yasmin and falls in love. Yasmin is the promised bride of Hedjah, the Prince of Algiers, who arrives with the fabled Pearl of Fatima as a gift for her. Soon after, a young street acrobat and thief named Tina sneaks into Yasmin's bedchamber and steals the gem. Infuriated, Hedjah promises to raze Tangiers to the ground in one month unless the pearl is recovered.
Mustapha tasks Yussef with the pearl's recovery and its thief's capture. To lure the thief into a trap, Julna sets up a fake lottery with a large ruby as the promised prize. Tina hides inside Yussef's coffeehouse to later emerge and steal the gem, but Julna and his adopted parents catch her in the act and find the pearl on her. Noting her agility as she tries to escape, Julna and Yussef decide to use her to slip into Mustapha's treasury. They return the pearl, but Tina secretly steals it back, which casts suspicion on Yussef.
When [Julna] goes to the palace to claim the reward, but learns of the new theft, he is seen by Yasmin, who ends up longing both for him and the pearl. This infuriates Tina, who has developed her own crush on Julna.
Eventually, Julna, Yussef and Tina sneak into the palace to plunder the treasury. They escape with a good portion of the gold, but the robbery is noticed. Yasmin, still desiring the pearl above all else, suspects Julna of having it and therefore offers her hand in marriage to him, only to have him killed after he has returned the pearl. Julna in turn suspects Mokar of having stolen it, so he intends to take it back from him. When Tina tries to stop him, Julna reveals his true identity to her, and now feeling unworthy of marrying him, she gives him the pearl.
When Julna enters the palace to see Yasmin, Tina sneaks after him and discovers the trap. Warned by her, Julna can escape, but Tina is captured and taken away to be questioned about the pearl's whereabouts. With the help of local street thieves, Julna attacks the guard train, triggering a running battle which ends with Julna's group cornered in the palace treasury. To stop the fighting, Tina threatens to destroy the pearl and identifies Julna as the true ruler of Tangiers. The guards, still loyal to their old ruler, instantly revolt against Mustapha; Mustapha and Yasmin are captured and banished from Tangiers, Julna assumes his rightful throne and takes Tina, with whom he has truly fallen in love, as his wife and queen.
