4. Teacher's Pet

Complete story — includes the ending

Shortly after encouraging Buffy, Sunnydale High's science teacher Dr. Gregory is attacked and goes missing. At a party, Angel appears and warns Buffy that somebody is coming. Miss French, a substitute teacher, has taken over Dr. Gregory's class, and the male students are immediately smitten. Buffy notices that Dr. Gregory's glasses have been left abandoned in his classroom. Later, Cordelia stumbles upon his headless corpse. Buffy investigates the death of a homeless man, suspecting it may be connected, and confronts a vampire she finds in the park. The vampire flees, encounters Miss French, and Buffy notices he is frightened by her. Buffy deduces that Miss French is a giant praying mantis. Buffy tries to warn Xander, but he goes to Miss French's house under the guise of helping her with a project. She drugs and imprisons Xander alongside Blayne, intending to use them to fertilize her eggs. Buffy and Giles track down the house and are able to kill She-Mantis in time to save Xander and Blayne. Under Dr. Gregory's desk, several mantis eggs begin to hatch.