Long after his experience in the Vietnam War, Bob Walker, like many veterans, still experiences the harsh effects of post-traumatic stress disorder (PTSD). He had little luck in dulling the pain — until discovering MDMA, commonly known as ecstasy. Though it has a notorious reputation as a party drug, Walker and others are convinced that MDMA’s unique qualities have the potential to treat the debilitating symptoms of PTSD that other approaches can’t.