A group of friends escaping the city for a weekend away have a simple plan, to tour the coast for a relaxing weekend. Things hit a snag when one of the friends spots a seductive, sultry young woman waving for help off the shore of one of many secluded islands along the coast. Reaching out to rescue her turns deadly and they risk everything to get off the island alive.
Siren contains examples of:
- Almost Dead Guy: Things start going seriously wrong for the protagonists when their yacht runs aground off a deserted island. Then an almost dead sailor swims from the island to their boat, babbles an incomprehensible warning (the sailor does not share a common language with anyone on the boat), and keels over dead.
- An Arm and a Leg: When Ken twists his ankle chasing after the phantasmal Silka, he wakes up on the boat with the dead sailor about to amputate his leg.
- Broken Heel: Aside from the Twisted Ankle described below, there is another sequence late in the film when Ken and Rachel are fleeing from Silka. Ken steps in what appears to be a shallow mud puddle. However, he then finds his foot is stuck and cannot be released: part of the magic of the island.
- Cell Phones Are Useless: The yacht runs aground in what seems to a black spot for cell phone reception. Later on, Rachel checks her phone and finds that the battery is completely dead. Both of these effects are implied to be a property of the island itself.
- Chekhov's Gift: Just before they set out on their voyage, Rachel gives Ken a pocketknife with 'Forever' engraved on the main blade. At the end of the film, Rachel stabs Silka in the neck with it after she has killed Ken.
- Covers Always Lie: One version of the dvd cover shows a bikini-clad woman (the head is cut off so it is unclear if it is supposed to be Rachel or Silka) holding a large knife; strongly implying that it is a Slasher Movie rather than the psychological/supernatural thriller it is.
- Deadly Road Trip: What was supposed to an idyllic weekend sailing trip turns into anything but when the yacht runs aground off a Deserted Island.
- Derelict Graveyard: Rachel and Ken discover multiple shipwrecks just off the coast off the island: having being lured in and wrecked by the siren. The protagonists had not seen this graveyard earlier as their yacht had approached from the other side of the island.
- Deserted Island: The island where the protagonists discover Silka has no one on it aside from her.
- Distracted by the Sexy: While driving, Ken is distracted by Rachel's legs (and higher) exposed by her skirt, to the point that he almost collides with a truck coming the other direction.
- The Drifter: At the start of the movie, Marco has been travelling the world for two years, trying to 'find himself'.
- Even the Girls Want Her: Silka's presence is enough to make Ken, Marco and Rachel desire her.
- Girl on Girl Is Hot: When Rachel and Silka are frolicking naked in the surf, Ken's reaction is "If this is a dream, I don't want to wake up".
- Harbinger of Impending Doom: After the yacht runs aground, a shipwrecked sailor swims aboard from the island. Deaf and bleeding from the ears, he babbles an incomprehensible warning before dying on the deck.
- Haunted House Historian: The primary function of the man who rents the main characters the yacht is to explain the legend of the siren.
- Interrupted Intimacy: Ken and Rachel are having sex in a public bathroom when Rachel has a psychic flash of a face looking at her. This freaks her out as she thinks someone is watching them, and she breaks off the coitus, much to Ken's frustration.
- It Won't Turn Off: When Marco is searching the yacht, he finds a tape deck in one of the cabins, playing a cassette of Silka singing. Marco removes the tape and the song stops for a few seconds. Then it starts again, despite there being no tape in the player.
- Jerkass: Ken seems to embody most of the unpleasant stereotypes of the yuppie. He also gives off an unpleasant 'rape-y' vibe around Silka.
- Making Love in All the Wrong Places: Ken and Rachel try to have sex in a roadside public bathroom, only to have the moment spoiled when Rachel have a psychic flash that causes her to think someone is watching them.
- Minimalist Cast: The film only has six speaking characters: Rachel, Ken, Marco, Silka, the dead sailor and the Mr. Exposition who rents out the yacht.
- Mind-Control Music: Silka is a siren, and her song has magical properties. Sung softly, it can hypnotise. Sung loudly, it can deafen and drive mad.
- Mr. Exposition: The primary function of the man who rents the main characters the yacht is to explain the legend of the siren.
- No Name Given: The dead sailor (who, despite his designation, does play a major role in events) is only identified in the credits as 'Dead Sailor'.
- One-Word Title
- Our Sirens Are Different: Silka is a siren, luring men to their madness and doom upon the island.
- The Radio Dies First: Once the yacht runs aground, the protagonists are unable to transmit or receive anything on the radio. It is implied that this is a property of the island.
- Reality Has No Subtitles: The Almost Dead Guy clambers aboard the yacht and babbles something to Ken, Rachel and Marco before keeling over dead. The trio have no idea what it was he was trying to tell them, as they do not speak his language. Neither does the viewer, as his words were untranslated.
- Sexy Soaked Shirt: When Rachel faints after getting a psychic flash when she touches the tree, she falls into the lagoon. When she emerges, her long white shirt is plastered to her bikini clad body.
- Shirtless Scene: Ken spends much of his time on the island shirtless and, when he does put a shirt on, he usually doesn't button it up.
- Show Some Leg: Rachel does this while hitchhiking at the start of the film: dressing in an extremely short minidress to flag down a lift. This turns out to be a sexual roleplay between her and Ken.
- Skinny Dipping: Silka entices Rachel to come swimming naked with her as the group is making camp on the beach. The sight is enough to make Ken and Marco join them. And then things get weird...
- Super-Scream: Silka is a siren. Sung softly, her song acts as Mind-Control Music. Sung loudly, it can cause deafness, madness and even death.
- Tainted Veins: When Silka resumes what is (presumably) her true form, her skin is waxy and translucent—like a drowned person—with black veins running beneath.
- Twisted Ankle: Ken trips while chasing after the phantasmal Silka and sprains his ankle, making him easy prey for the dead sailor. The next morning, his ankle is fine, calling into question how much of those events were real.
- Why Are We Whispering?: Ken, Rachel and Marco have a whispered conversation about Ken's plan to bury the dead sailor on the island and pretend they were never there. Marco asks why they are whispering, as it is only them and the dead sailor on the boat.
- You Kill It, You Bought It: At the end of the film, Rachel is shown to have become the new siren of the island after having killed Silka.
