What if you couldn’t feel pain — ever? No burns, no broken bones, no warning when something’s wrong. In this episode of Medicine, Mystery, Mayhem & Murder (M⁴), we explore a condition so rare that those who have it can bite through their tongues, walk on fractured limbs, and never realize they’re hurt. We’ll uncover the science behind the missing pain receptors, the genetic clues that explain it, and the heartbreaking human stories that remind us why pain, as cruel as it seems, might be one of the body’s greatest gifts.