This week, we meet a girl whose heart has formed outside her ribcage, a man who can spend nine minutes underwater without taking a breath, a woman who is growing a second skeleton and a paralysed man who is regaining movement thanks to a chip implanted into his brain that can 'read' his brain signals.

In this episode, we take a look at the human body's amazing capacity for survival. We meet a man who injects himself with deadly snake venom, a woman who leads a normal life with only half a brain, a girl who collapses 50 times a day and the only man in the world to be completely cured of HIV.

This time, we meet a man who feels no pain, a woman who can smell Parkinson's disease, a man who can remember every face he has ever seen and a survivor of a head injury who woke up to find he could suddenly play the piano.

This time, we meet a girl with two hearts, a man who can sing two notes at once, a woman who can bend in amazing ways, a girl who is allergic to everything and a man who can run 350 miles without stopping. These remarkable cases reveal the secret inner workings of our bodies - the ultimate piece of natural engineering.

This time, Gabriel uncovers the stories of a man with bones as strong as granite, a woman who became pregnant with twins in two separate wombs, a girl whose arm won't stop growing and a woman who gets lost in her own home.

In this episode, Gabriel uncovers the cases of an engineer who fixed his own heart, a toddler whose bones were repaired before he was even born and a girl whose immune system attacked her own brain.