Scooby-Doo! Mystery Incorporated S01 E11 The Secret Serum

"The most hauntedest place on Earth."

There's a vampire loose in Crystal Cove, terrorizing the residents and stealing an odd assortment of loot. When the gang does some sniffing around, they discover an unlikely suspect… Daphne's MOTHER. Things are already strained within Mystery Inc., and with this latest blow, the gang is truly torn in half. Girls on one side, boys on the other.