The Real Ghostbusters - Season 2 - Eps 48: Apocalypse -- What, Now?
The Canon of St Theophilus, a book missing from an abbey in Greece since the 1860s, turns up at a New York auction and is accidentally purchased by Peter. Unbeknownst to the Ghostbusters, the sealed volume contains within it the Four Horsemen of the Apocalypse.
About The Real Ghostbusters

Title: The Real Ghostbusters
First Air Date: 1986-09-13
Last Air Date: 1991-10-05
Status: Ended
Rating: 7.7/10 (from 269 votes)
Language: EN
Seasons: 8
Total Episodes: 140
Network: ABC
Genres: Action & Adventure, Animation, Comedy, Kids
Production Companies: DiC Entertainment, Columbia Pictures Television
Synopsis
The continuing adventures of paranormal investigators Dr. Peter Venkman, Dr. Egon Spengler, Dr. Ray Stantz, Winston Zeddemore, their secretary Janine Melnitz and their mascot ghost Slimer.
Cast

Maurice LaMarche
Egon Spengler (voice)

Dave Coulier
Peter Venkman (voice)

Frank Welker
Ray Stantz / Slimer (voice)

Kath Soucie
Janine Melnitz (voice)

Buster Jones
Winston Zeddemore (voice)

Rodger Bumpass
Louis Tully (voice)