Wolf Apples?

Have I read that tomatoes are related to Nightshade?
Is my recent info on tomato plants cleaning the earth by processing the 'bad stuff' and filtering it into the fruit?

What happened in the movie "The Last Supper"? They ate their lovely crop of tomatoes while coming unhinged. I can't remember if it was supposed to be a psychological break down within the group or whether it was supposed to have something to do with the lye (or whatever they doused) under the tomato plants..