Dark Shadows - Season 6 Episode 228 DS-691 Necking in the afternoon.
Overview: Quentin tries to strangle Maggie, Elizabeth and Julia walk in and he disappears. Maggie tells Elizabeth that David and Amy are possessed; later they find the children begging Quentin to leave them alone. Elizabeth and Mrs. Johnson find David and Amy passed out and they hear the sound of Quentin’s music and laughter throughout the house.