I have seen every single episode of "Thriller" save one....and that one ("The Last of the Sommervilles") is only available on the DVD set...and I'll be getting to that one very soon. But I can pretty safely say that "Portrait Without a Face" has a distinction....the single worst performance of any actor in any episode. The character 'Agatha' (Katherine Squire) is simply horrid...cackling like a derranged witch who is on crack!! Nearly every scene that she's in, she's screaming/cackling insanely...and I have no idea why she played it that way or why the director allowed her to do it. It nearly ruined the episode...it was THAT bad!
A famous painter is murdered brutally--with a crossbow bolt in the eye! Who did this is unknown and appears to be something they'll never know. However, when an expert from an auction house comes to examine and catalog the collection of paintings the artist left behind, something super-weird happens. There is a nearly blank canvas...the same one the artist was working on when he was killed...and it shows his death! Now, only a small portion of the painting has been done...but over time, when no one is looking, the painting continues to fill itself in and promises to eventually show the murderer as well! How could this be??
For the most part, this is a non-supernatural episode posing as one. And, since it's more a murder mystery (like the earliest and worst episodes), I found the conclusion very disappointing....as well as that god-awful cackling!! Because of these factors, I am rating this one only a 4. It could EASILY have been a 7 or 8 or 9...if the script didn't wimp out and if they'd just killed the housekeeper instead!!
By the way, I am not the only one who hated Agatha...a couple other reviewers found her performance hellishly bad as well.