The Dark Age

In which Giles' past is revealed, Buffy is decorated, Jenny is possessed, and Ethan is back.

Official back-of-box synopsis:

The future doesn't look bright for Giles or Ms Calendar. Giles' quiet existence is jeopardized when a murder victim is linked to his past, and Buffy and Angel look for a way to save Ms Calendar from a demon that has taken possession of her soul.

From the old WB Buffy website:

RUNNING FROM THE PAST -- Giles' quiet existence in Sunnydale is jeopardized when a murder victim, who is found to be linked to Giles' past, is discovered on the steps of the school library. Meanwhile, when the Mark of Eyghon -- a demon that takes possession of a dead host -- takes over Ms. Calendar, Buffy and Angel discover the one way to save her soul.

Links:

This episode's page at http://www.restlessbtvs.com/, the Restless BTVS Trivia Guide

This episode's page at http://www.vrya.net/bdb/, the Buffyverse Dialog Database

Cross-reference:

episodes in which our heroes get drunk:

• Beer Bad
  A Very Special Buffy
• Something Blue
  Willow's "Not drowning, wading" in light beer
• A New Man
  Giles -- again -- too many beers with Ethan
• The Yoko Factor
  Giles - whisky - again
• Life Serial
  Buffy - Tequila - priceless look on her face
• Entropy
  Spike and Anya. Hilarity ensues. Oh, wait, not hilarity.
• this episode
  Giles - whisky

Cast:

• Sarah Michelle Gellar as Buffy
• Alyson Hannigan as Willow
• Nicholas Brendon as Xander
  

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• Anthony Stewart Head as Giles
• Charisma Carpenter as Cordelia
• David Boreanaz as Angel
• Robin Sachs as Ethan
• Stuart McLean as Philip Henry
• Wendy Way as Deirdre
• Michael Earl Reid as Custodian
• Daniel Henry Murray as Creepy Cult Guy
• Carlease Burke as Detective Winslow
• Tony Sears as Morgue Attendant
• John Belluci as Man