Mikey was trying all day to get his brothers to know it was his birthday...but his brothers acted like they forgot so they can plan a surprise party when Mikey leaves. However, they were not wanting their forgetful gag to go too far as their young brother ran away. "I knew we should have stopped...now he's mad at us..." Leo says.

"Well lets not sit around...lets go." Donnie says and he and the others went to find their missing brother. What they were not expecting, was Shredder to find them...and use a reverse mutagen the three, Leo, Raph, and Donatello turned back to box turtles.