In the mid-15th century, a legend about the King's Heart circulated across the most prosperous Adventure Kingdom on the central continent—whoever finds the King's Heart shall become the king. Princess Margina (voiced by Ye Fang), known throughout the Adventure Kingdom as the "Cowardly" Princess due to her timid nature, had never experienced a real adventure. Though she had been striving to inherit the throne, her qualifications were questioned at the royal ball where the king was to announce the successor. Determined to prove herself and fulfill her dream of becoming king, she escaped the ball and teamed up with Alibaba (voiced by Ding Yan), a boy from the slums. Armed with the "Treasure Guide" given to her by the king, she and Alibaba entered the mysterious and thrilling treasure vault world, embarking on a journey to find the King's Heart. Also entering the treasure vault were a trio of ruthless bandits. They subdued the Mirror Monster and formed a powerful gang known as the Forty Thieves. The bandit leader sought to obtain the King's Heart and establish a bandit kingdom, and unpredictable dangers crept closer and closer to the princess and Alibaba. In the end, the princess and her team overcame the numerous perils within the treasure vault world, and Alibaba fulfilled his wish of defeating the bandits. The princess obtained the King's Heart and came to understand the most essential qualities required to become a king, growing and maturing through her adventures.