It's easy to see why this appealed to a teenage horror movie fan in the 60s, although while I expected it to be pretty tame nowadays it actually had some appreciably dark edges that are just as impactful now as they would have been then.

I only watched it after seeing an interview where Stephen King extolled the virtues of the underwater sequences and despite it being kind of melodramatic and a bit of a potboiler I was pleasantly surprised. It's of course also worth watching as one of the first (if not the first) directing gigs by a young man named Francis Ford Coppola.

As a Roger Corman production, it came with some nifty horror flick gimmicks – as the poster promises, 1963 audiences were to be asked if they'd ever been afraid of death by drowning or felt like committing murder before they'd be admitted to the theatre. But aside from the era-appropriate camp of the marketing (even the poster art makes it look like a video nasty from 10 years later) it's plain Coppola wanted to make a pretty serious horror drama.

Louise (Luana Anders) and her husband John have a fractious relationship, so while they decide to go rowing in the middle of the night is a mystery. They argue about his mother's fortune, which Louise knows she won't get a dime of if he dies first.

So when Richard suffers a fatal heart attack and drops dead right there in the boat, Louise hatches her nefarious plan to hide his death from his family, dumping his body over the side and telling them she's coming to visit in their stately home in Ireland while he's away on business. She intends to worm her way into the family's good graces and only then reveal the truth somehow when she has her hands on their fortune.

Her husband's younger brother Billy believes and accepts Louise into the fold, but his older brother Richard seems to suspect, treating Louise with barely-concealed contempt.

But she sees her chance after witnessing a bizarre ceremony where the two surviving brothers and their mother grieve over a marker for their long-dead sister/daughter Kathleen. When the aged matriarch faints dead away thanks to the sadness she can't get over, Louise knows what she has to do.

Collecting dolls from Kathleen's room (untouched since the girl's death years before), she swims to the bottom of the lake on the property to deposit them amongst the reeds in the middle of the night, figuring they'll float to the surface and convince the crazy old woman Kathleen's ghost is trying to contact her.

But she sees to her horror what appears to be the girl's perfectly preserved corpse on the lake bed, and when she surfaces in a panic hands grip her violently, pull her from the water and murder her with an axe. It's the second most shocking character death in a 60s film after Psycho .

With Louise now missing as well as her husband, the stoic, logical family doctor visits to try and solve the mystery. It's all to do with the secret family history, how Kathleen died and the (again, nodding to Psycho ) cracked psyche at the centre of it all that you least suspect.

Corman's notorious cheapness gives it a low fi approach that actually works well for the subject matter and genre, looking and moving a little bit like Night of the Living Dead. It would have been hard to make something to stand the test of time thanks to the social mores of the day, but even without showing any brazen nudity or violence, Coppola does a good job with a moody, dank thriller.

Originally part of a double bill with X: The Man with the X-Ray Eyes starring Ray Milland, Coppola pitched it to Corman by describing the central murder sequence and the producer immediately gave him $22,000 to make it, unaware Coppola went looking for more money elsewhere and got the same amount from someone else.