Sometime in (I think) the early 80s there was a "Twilight Zone" type of television show (the scary short vignettes sort of thing) that featured this episode: Historical piece, takes place in France, young rogue (probably a thief, I forget) is condemned to death by guillotine. His girlfriend plots to set him free. Tradition says that if the executioner dies, the next man who was to die will be set free instead. The girl sleeps with the official who can tell her what day her lover's scheduled to die, then, armed with that knowledge, sets out to seduce the executioner. The executioner (naturally a lonely pariah) grows exquisite roses; she catches his eye by pretending to be a rose-seller, displaying roses that she has secretly dyed a brilliant color. She pretends to befriend him, has dinner with him at his home, sleeps with him and in the morning (the morning of the execution) poisons his breakfast porridge. (There's a bit where the executioner's housekeeper serves fruit for dessert the night before and the girl says something like, "Thank goodness! When I saw the cake batter I thought we were going to have one of those too-rich desserts." The housekeeper coldly says it wasn't cake batter, it's porridge for monsieur's breakfast tomorrow.) Her lover is jaunty on the scaffold in the town square that morning, knowing the plot. The executioner proves to be of exceptional constitution and actually makes it out of his home and to the square, but collapses. When the condemned man demands to be set free as tradition dictates, the collapsed executioner sees the girl standing over him, who squeaks "Die!" at him under her breath. He understands the whole plot at that moment and with his last strength gets to his feet and to the scaffold, as the condemned man is forced into the guillotine, panicking and screaming (girl also panicking and screaming). The executioner gets as far as raising the guillotine blade, then collapses next to the scaffold. A doctor picks up the executioner's hand to check a pulse, pronounces him dead. "I win! I win!" screams the condemned man from the guillotine. The doctor drops the executioner's hand--which falls, dead weight, upon the release bar for the blade. Shot of the blade just beginning to fall, cut to black.
What the hell was the name of this show/episode?
ETA: Found! Through the grace of bethbethbeth and a little internet persistence on both our parts, it's "Guillotine," an episode of the '81-'82 series Darkroom, hosted by James Coburn. Not on DVD, it appears. Well, I have a place to start looking, at least!