Have you ever thought about your heart? Have you ever thought about how important your blood is to your life? Of course you have! But what would you say if I told you about a fellow by the name of Leo Foster, who had two hearts! You'd say that I was barmy - but the facts are, that Leo's blood was being pumped by a second heart for a brief time. Yes, a real human heart! But that's enough of the riddle, lets get into the story...