"Psilocybin does in 30 seconds what antidepressants take three to four weeks to do," David Nutt, a professor of neuropsychopharmacology in the division of brain sciences at Imperial College London explains in the film. Researchers have found that a single dose of psilocybin accompanied by therapy can have a transformational effect on mental health — like a "surgical intervention" — able to treat even cases of depression and anxiety that resist standard treatment.