Harry Caulder (David Huffman) works on the beach and in the sea as part of the coastguard of this area of California, and likes to swim to work as it's not too far from his home. This morning he spots Mrs Hutton (Harriet Medin) as she walks her dog, and greets her with a cheery hello, as Harry used to go out with her daughter Catherine (Marianna Hill), but when he enters the water he starts to hear screams and looks round to see what is happening. He doesn't catch it, but Mrs Hutton has been sucked down into the sand by some unseen creature; the police are now involved, but what can you do against a menace that is practically invisible?
Here is one of those "What was the movie where?" films, you know the type of thing, it has one element that sticks in the memory when the rest of it is lost in the mists of time. Here that element was the modus operandi of the monster, so this was the "What was the movie where people kept getting sucked under the sand?" effort, and the dimly recalled answer was Blood Beach. It did have other notable aspects, for example it was one of the few leading man roles its star David Huffman secured before his murder a few years later, but the downright oddity of the manner in which the victims were dispatched with eclipsed all other parts.
This is none too surprising when you actually watch it to find that much of the plot is taken up with what could essentially be described as padding, with long conversations that pretty much go nowhere, and a tone that acknowledged how daft its premise was but stepping back from outright spoofery. There are scenes played up for their humorous angle, such as when police chief John Saxon delivers the immortal line "Just when you thought it was safe to go back in the water you can't get to it", which also emphasies the film's main influence. Yes, it was one of those Jaws rip-offs, only evidently director Jeffrey Bloom thought, forget all that ocean stuff, let's hit the beach.
The logistics of dragging an actor beneath the sand apart, this must have been easier to film on land than going out to sea, so you can sympathise with the filmmakers in wanting to take the less arduous path. Trouble is, the less arduous path included acres of relationship drama as Catherine returned to the Californian town to find out what had happened to her mother only to rekindle her affair with Harry, this in spite of the fact he already has a girlfriend. Well, the monster takes care of that, freeing up Harry to begin afresh with his old flame, which leaves you wondering if he's working in collusion with it. Certainly there would be a few soap operas enlivened by the addition of a character-devouring beach thing.