A diverse group of people quarantine themselves on a small Greek island to prevent a suspected plague from spreading to the army camped nearby on the mainland. As they wait for the disease to run its course, a hardbitten general (Boris Karloff) comes to believe the superstitious ramblings of an old woman (Helene Thimig) that the young maid (Ellen Drew) is an undead monster who is preying on their life force.
"Isle of the Dead" is one of the last in a string of legendary horror films that producer Val Lewton made for RKO. It is also one of the weakest, with an uneven script and a cast with acting styles that conflict; Emery and Thimig are chewing up the scenery in old-fashioned monster-movie style, while Drew gives a subtle performance that belongs in a romance film, while Cramer is just bland.
Karloff gives a mostly disappointing performance, seeming as if he is sleepwalking through the picture. The only time he comes alive is when his character makes a failed attempt at self-reflection. He manages to bring a little bit of menace to his role, but that's mostly attributable to the fact that the other actors in the picture have so little presence
Worst of all, the film has a terrible script. For most of its running time, the movie simply unspools in a dull fashion. The characters are on a supposedly plague-infested island, yet their behavior feels more like they are on just another vacation. This lack of tension is augmented by one of the worst insta-romances ever put on screen when the Greek maid inexplicably falls in love with the square-jawed and utterly bland American war correspondent (Marc Cramer)over the space of a day they hardly see each other.
However, if you stay with the film, things start to get a lot more interesting in the last 20 minutes. From the kindhearted maid being tormented by the old crone through a closed door, to a mad killer stalking (and skewering) the surviving inhabitants of the island, we finally get to experience some of the dread and darkness that should have been present in at least a small degree from the very beginning of the film.