A woman is possessed by the spirit of her husband's first wife, an evil temptress. It's all tied with a mysterious devil worship cult on the island.
This potentially interesting idea is a little like a cross between two Bert I. Gordon films, TORMENTED and NECROMANCY; it's particularly reminiscent of the former, with its lapping waves and dead lover motifs; unfortunately, the movie is hoodwinked by terribly dull direction and a badly muddled script. There are too many scenes of people visiting the couple and being treated coldly by the possessed wife, and there are a number of events in the movie that either lead nowhere or abruptly come out of nowhere; the script definitely needed a rewrite. A check at IMDB indicates that the director mostly worked on westerns; he certainly doesn't feel at ease here in the horror genre. It also contains the worst "someone's favorite song" that I've had the misfortune to hear; it's fast, aggressive, jazzy, horrific and horribly annoying, but at least it doesn't have lyrics, and you'll be glad when the record gets smashed.