Episode 210 is where Willie Loomis becomes interested in the portrait of Barnabus Collins on the wall at Collinwood. It is said to be the real beginning of the supernatural episodes of the show.
Only four characters in this episode, none of which I remember from the later story arcs I saw on Sci Fi in 2000.
Willie Loomis becomes persona non grata at Collinwood. He is fired, and to be sent away, but before he can be found has entered the Collins family crypt to pry open the coffin of Naomi Collins. While attempting to do so he opens a door and we hear a heartbeat. The Dark Shadows theme comes up, and we go to commercial. When we return from what must have been a television commercial...
We see Willie Loomis excitedly working to remove the chains from a coffin. The heart beat continues, and after Willie excitedly pries open the lid of the coffin he recoils to find...
The Hand Of Barnabus Collins?
Interesting tidbit of trivia: the hand of Barnabus Collins is not portrayed by Jonathan Frid, but by Timothy Gordon.