Casey Jones was training under Master Leonardo, learning everything he could from him.

This was during a terrible time—a huge war with an alien race called the Krang. The Krang had taken over Earth and destroyed most of it. Only a few people were left: Master Leonardo, Master Michelangelo, and a small group of survivors, including Casey.

The two masters knew they couldn’t win. So, Michelangelo used all of his mystic power to create a time portal, even though it would cost him his life. Before the Krang could strike again, Leonardo pushed Casey through the portal—sending him back in time with one mission: to stop the war from ever happening.

A few hours passed.

Casey found himself in the middle of New York City, but everything looked different. He quickly realised he had traveled back to a time before the war—when the turtles were still teenagers.

While trying to find them, Casey got caught and woke up tied to a chair. Standing in front of him were the younger versions of Leonardo, Raphael, Michelangelo, Donatello, and Master Splinter. They looked nothing like the battle-hardened warriors he knew—just teens.

After a long talk, Casey explained who he was, where he came from, and what the Krang would do in the future. That’s when he realised something important: Master Michelangelo had accidentally sent him back too far. He had arrived a whole year earlier than he was supposed to.