There is no diary. There never was. The book this is based on was written by Beatrice Sparks, a therapist who specialized in anti-drug propaganda. She wrote several other similar books, all of them by "Anonymous." I'm not pro-drug, not at all, but I am pro-TRUTH. If the author had put her name on this, said it was a novel but it was based on a number of patients she had treated for drug addiction, I would have no problem with that.
I first read the book when it was originally published in 1971, then again about ten years or so ago. I don't remember all the details but I do know it was more interesting that this movie, which has all the hallmarks of an after-school special. Yes, I know some people got into heavy drugs back then, but millions of people smoked pot for a few years and then gave it up once they got out into the "real" world (and started drinking, just like her parents). And yes, I knew people who had LSD or other hallucinogens slipped into their drink without their knowledge. Most of them swore off drugs entirely.
This whole story is obviously written by someone who was an adult at the time, trying to imagine what it was like to be a teenager, probably based on stories she'd heard. I graduated high school in 1971, the year the book was published, so I actually was a teenager at the time, although a couple of years older than "Alice." Watching this movie makes me want to make a movie myself about what it was ACTUALLY like to be a teenager back then. At least it would be honest - and truthful.