Halloween
Original air date: October 27, 1997
It's Halloween night, the night when most vampires stay in. But that doesn't make it a quiet night. Buffy, Xander and Willow are forced by Principal Snyder to participate in taking the kids trick-or-treating. But everyone turns into whatever they were dressed as, Buffy being an 18 Century Noblewoman, has no memory of who she really is. Cordelia is the only one who doesn't turn into her costume , making Willow and Giles realize she was the only one who didn't buy her costume at the new store, Ethen's.
This was a really good episode. We see Spike videotaps Buffy slaying a vampire to learn her moves, so it will be easier to defeat her, and he almost gets his chance when she is helpless.
Also, we learn of Giles' connection to Ethen, although we don't know yet just what, but we learn that maybe Giles wasn't always the good guy.