In "Teenage Mutant Ninja Turtles III," the four turtles—Leonardo, Michelangelo, Donatello, and Raphael—are transported back in time to feudal Japan. They must rescue their friend April O'Neil, who has been captured by a villain named Lord Norinaga. The turtles face various challenges as they adapt to the new environment and culture. To defeat Lord Norinaga and his forces, the turtles team up with a group of rebels led by Yoshi. Together, they engage in battles and use their ninja skills to restore peace. The film combines action, humor, and themes of friendship and bravery.