Fighting Machine.

Fighting Machine
Following the events of 03 - Baptism Of Fire, Tiffany returns from a holiday with no apparent memory of being a vampire slayer the morning after Daria accidentally lets slip that she is in fact Daria Morgendorffer, not Joy Merryweather.

it is eventually revealed that Tiffany, along with a lot of other slayers that have been dissapearing, were being committed to nut houses because their parents were being influenced by the First Evil, and when the First Evil's involvement is revealed, it all kicks off.

The Watcher's Council is under seige as it is suspected to be a terrorist organisation, and after the first evil recreate's Tara's death in view of police snipers, the 22nd regiment, in a near repeat of Operation Nimrod, are sent in to clear house.