Splinter goes away and leaves Leonardo in charge. After a while, Donatello, Raphael and Michaelangelo get tired of being bossed around by Leo and decide to try one of Don's inventions on their hapless leader. The 3 scheming TMNT zap Leonardo with a "Personality Modifying Ray", turning him into a wise cracking jokester. It doesn't take long for the new Leonardo to annoy the Turtles once again.  Meanwhile on the surface, the City is being destroyed by a criminal musician named G. Cleff. Cleff is using an ultrasonic sound system to shatter concrete and steel so that his goons can rob the buildings.