Phineas and Ferb meet Leonardo Dicaprio

After looking at an Leonardo Da Vinci exhibit in the museum, Phineas and Ferb wonder what it would he was like as a kid. They use there time machine to visit Renaissance Italy, only to find "Leo" is a fragil boy. They accidentally take him back to the present, where Leo becomes interested in the modern day world. Unfortunatley without Leo in the past, the modern world finds itslef reverting back to the middle ages. Phineas and Ferb must find Leo and bring him back to his time.