One of the best episodes in a long time. Virtually everything clicks, maybe because the episode focuses on core characters and keeps the kids and the spooks off screen.
The possession seems to affect Carolyn much differently than it does the children. She's haughty with Julia, condescending with Willie and dismissive about Maggie and Barnabas. I wonder if the business with the cookie was an acting choice that Nancy Barrett made. Carolyn has survived so many things virtually unscathed but she seems headed towards the madwoman that we saw in 1995.
Barnabas is short with Willie and pompous with Julia. Both are in character. Both are annoying.
Maggie is pretty close to dying here, so it's up to Willie and Julia to track down the mystery vampire. They are remarkably successful. Julia is shocked when she recognizes who is in the casket. One of the best Friday cliffhangers of the series!