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Kills his lover instead of his wife, tries to murder wife too, begins and almost ends on the beach

Ends with husband who is attempting to murder his wife after killing his mistress by mistake, is buried alive in cement, causing it on himself when trying to pull himself out of trench.

Opening scene a man is shown running after a woman on the beach and trying to drown her. She is running away from him but finally he catches her and holds her head under the water.

 

In later scenes we find out that he has a mistress lover to whom he promises he will get rid of the wife. (Perhaps in a conspiracy - don't remember). But it turns out that the lover goes to the house wearing this big hat (which makes him think she is the wife) and he kills her and buries her (in cement?) leaving no evidence. He then comes home and finds his wife who is unaware of anything wrong. He is extremely scared and finds it hard to breath. He realizes that he murdered the lover.

The wife somehow finds out about the murder and his intentions and the movie ends with him running after her, with the scene from the beginning of the movie. But then she throws sand in his eyes, and runs out of the water and onto the beach, where there is a cement project (if I recall where he buried the lover and intended to bury the wife). He falls in and asks for a hand. She thinks of reaching over when a wooden stick is moved and the cement is scene pouring into the place where he is standing.
asked Oct 26, 2015 in Name That Movie by pashute (14 points)
edited Dec 30, 2015 by pashute
I remember the scene where the man in the trench reaches up and grabs a board to pull himself up.  the board breaks and allows the walls to open pouring wet cement over him covering him up.  This would have been 1969 to 1975 on ABC, NBC or CBS.
I saw it in 1982 or 1983 on Israeli TV
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