The film follows a pioneering team of scientists and psychotherapists led by Professor David Nutt Dr Robin CarhartHarris and Dr Rosalind Watts as they compare the effects of psilocybin the active ingredient of magic mushrooms with an antidepressant an SSRI called escitalopram on a small group of participants with clinical depression This is scientific research at its most cutting edge With over seven million people being prescribed antidepressants each year in England alone this drug trial is an important milestone in understanding a completely different treatment for depression