The Black Pit of Dr. M

Movies and TV from the Buffy show all the way back to 1960 have been ripping off the dig-myself-out-of-the-grave scene, evidently begun with this film (correct me if I'm wrong). The idea could be as old as Poe but it's this film which, in my history, succeeds with the definitive version. As mentioned earlier, two doctors in charge of an asylum agree to contact the one living, should the other die first. The theme played on the violin by Dr. M is recapitulated at different plot points in a way that earlier audiences would recall from opera.