Boris Karloff's name is what brought me to this picture, and without him, I think, the film might have been just another B movie programmer from the Forties. I've just learned a little about producer Val Lewton, and their collaboration here is what gives the picture some of it's momentum. While watching however, I never really got the impression that this was going to be much of a horror film. Yes, there's mention of evil spirits and malignant forces, and even a word about the dreaded vorvolaka, an undead vampire-like creature that's part of Greek folklore. But even with a mysterious Madame Kyra (Helen Thimig) professing such belief, and others in the story buying into it, the production makes it pretty plain that the reason folks are in danger is because of a plague that has infected the island. The attempt to link Thea (Ellen Drew) to malevolent forces didn't really work for me, she was just too wholesome and good looking to imply a serious threat. That role should probably have gone to Madame Kyra, perfect for someone warning about vorvolakas to actually be possessed by one.
What works best I guess is the way General Pherides (Karloff) slowly unravels from a man of strong principal and belief in science to a mad man intent on eliminating a superstition come to life. It's that psychological aspect to the drama that holds more water than the implied horror component, even if Mrs. St. Aubyn escapes from her coffin. Enough explanation revealed her bouts with cataleptic trances and fear of being buried alive to make that an expected part of the story, and one would presume that that was enough to put her over the edge with the old Poseidon sword.
Nevertheless the film is enjoyable on a number of levels; for one, lovers of old films will delight in the great ambiance of an isolated, wind swept island and the dark, moody atmosphere of the Albrecht home. The characters never wear out their welcome, and as others on this board have suggested, those that might have make an early exit. Be prepared though for a Karloff you haven't seen before, all the while I just couldn't get used to seeing him in a military uniform with curly hair.