Whitney Dylan

A demented patient causes a shootout in the emergency room. After terrorizing people in the ER with a gun, she gets shot by a policeman. She soon dies. Benton later discover her dementia was caused by an aftereffect of his surgery that he and Cleo should have detected. Carter pursues a cute intern. After a particularly long surgery, Corday decides to take her maternity leave. And April Fool's pranks abound in the ER.

Piper is abducted by The Source and comes dangerously close to relinquishing her, and her sisters powers.

While the gang battles creatures from the Hellmouth, Xander has his own adventure when he encounters a group of reanimated corpses out to blow up the high school.