Serling and the Turtles are working on their surprise birthday party for Cody when all of a sudden the Turtle X suddenly starts going out of control. It turns out the fugitive Darius Dun planted a "Trojan Horse" virus in Cody's exo-armor and is now controlling Turtle X to enact his revenge on his nephew and the Turtles. The guys have to work together to take down the deadly Turtle X — a prospect made all the more difficult when Cody gets trapped inside!