Of all the wonders of the human body, there's one more mysterious than any other. Blood: five precious litres that keep us alive. Yet how much do we really know about this sticky red substance and its mysterious, life-giving force? Michael Mosley gives up a fifth of his own blood to perform six bold experiments. From starving it of oxygen to injecting it with snake venom, Michael reveals the extraordinary abilities of blood to adapt and keep us alive. Using specialist photography, the programme reveals the beauty in a single drop. Michael even discovers how it tastes when, in a television first, he prepares a black pudding with his own blood. Down the ages, our understanding of blood has been as much myth as science, but Michael reveals there might be truth in the old vampire legends, as he meets one of the scientists behind the latest research that shows young blood might be able to reverse the ageing process - the holy grail of modern medicine.