A new documentary series called "The Dark Side of Comedy" sheds light on Robin Williams' struggles with drug addiction. Close friends of the late comedian, including Allen Stephan and Mike Binder, reveal that Williams was highly addicted to cocaine and couldn't perform without it. However, Williams eventually reached a turning point and managed to quit drugs after the death of John Belushi and the birth of his first son. The documentary highlights the destructive nature of Williams' addiction and the challenges he overcame during his career.