Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
"Only the cobra could satisfy her unearthly desires."
"She sucks the life from the bodies of men!"
This is a horror thriller without much horror or thrills, starring Joy Bang. With a name like that, she could have been a porn star, but this is not porn, though there are a few scenes with nudity - that was a requirement of '70s grindhouse flics. Mostly this a full-on snake movie from start to finish. Who needs a good plot when there are so many snake scenes - so many that the snake handler Gelacio Erica gets a predominant credit. The actors hold real live cobras and cobras crawl on them and around their necks. In some snake close-ups you can see stitches where they sewed the snake's mouth closed, and it's possible they also had their fangs or venom glands removed. (Maybe in the Phillipines in the early '70s you could get away with endangering the actors and abusing the animals. They wouldn't get away with it now, they'd have to use those awful CGI snakes.)
The action starts in the Phillipines during World War II when two nurses hunting for herbs discover a snake worship cave. One of them, Lena, is bitten by a cobra with a red diamond on its throat that we later learn is a "firebrand cobra" named "Movini." Lena also develops a red diamond on her throat and her eyes get waxy. Then she returns to normal and carries the cobra to the other nurse Francisca who has been raped and shot by a Japanese soldier. The cobra cures Francisca and the next thing we know, it's 27 years later and we're watching a man milk a cobra of its venom. Another man lectures the audience that the purpose of many of the enzymes in the venom are not understood, etc. The scene prepares us to believe that a cobra's venom is only fatal if the snake is angry, otherwise it can do other things, like keep you eternally young, or fertilize plants, as we will see later.
In order to stay young, Lena must milk the venom of Movini and use it on herself. If she doesn't get her venom fix, her skin starts to shed and the red diamond on her throat returns. Then unless she has sex with a healthy young man, she will get old. Afterwards, the men become deformed and wrinkled like old men because she has sucked the years from them. After one of her sex cures, we see her perform a full-body exfoliation procedure that makes her look normal again.
Joanna, a young American woman who is doing field research developing anti-venom, decides to study the venom of the firebrand cobra after learning of its magic qualities. She goes to see Lena the cobra woman, and soon Joanna's boyfriend Duff (who always wears a shirt with his name on it) visits Lena and gets bitten by Movini. Lena sucks out the venom and heals him. Then she uses him for a sex cure and that makes him dependant on her to stay young.
After Joanna steals some cobra venom from Lena, Movini climbs a tree to drop down and kill her, but the cobra falls on Francisca and kills her instead. Then Movini crawls towards Joanna, But Joanna opens an eagle's cage and sets it free to attack the snake. The eagle fights and kills Movini. After her cobra dies, Lena passes out and her eyes get waxy again.
Turned into Movini, Lena goes to the snake cave to pray to a snake god to let her return permanently to her rightful serpent form. We see her transform from a human to a snake in some not very special effects that consist of a few double exposures. But Francisca's son Lope wants to get revenge on Lena/Movini for making him deformed and for killing his mother. He comes into the cave after Lena is turned into a cobra and hacks the cobra into many pieces. Each piece then transforms into a complete cobra and one of them kills Lope. The cobras crawl into Lena's house and attack Joanna, but Duff finds her and commands the snakes to leave her alone. He tells Joanna to go away for good. It's hard to know what happened and what will happen, but apparently there are now a lot of firebrand cobras and Duff seems to be the new person in charge of them.
After the cobra Movini comes after Joanna, she releases an eagle from its cage and the bird fights the cobra. The fight is heavily edited, but it looks like it's real, with a real snake and a real bird, though I don't know if it is an eagle or another type of bird or if the snake is a real cobra. The snake loses the fight. After it dies, Lena, the snake woman, falls to the ground and returns to the state she was in after the cobra first bit her.