CrazyDaisy

Hey, I am trying to remember the name of a Halloween cartoon special I saw when I was a little girl. It was in the 80's when I saw it but it could've been made in the 70's or 60's. The animation was a little artsy, a character's hair, skin and clothes were all one color. Anyway, it was about a brother and sister who were dressed up in their Halloween costumes and somehow they, along with neighboring children, were transformed into the monsters they were dressed up as. I only remember bits and pieces but it's been driving me crazy for years and I can't find anyone who recalls anything like it. I believe it aired on CBS, NBC or ABC - one of those basic networks. So if anyone has any ideas of what it might be I would be so thankful for even suggestions. Thanks!