The story involves six teenagers who head to mysterious isolated island for a weekend of partying. Trouble is, the island has a dark and ancient history, of a sacrificial rite held during the so-called "blood moon" that is meant to keep the "devouring ghost" at bay. And of course, these kids are visiting the island during that very time.
But let's back up a bit, to the boyhood of the title character Thongsuk. He was always not quite right and a bit sickly. It's in the school infirmary where he's resting and his best friend Nam comes with a headache. Thongsuk, wanting to impress the girl, has her take off his amulet necklace, which is supposed to ward off ghosts. She does so and Thongsuk immediately lapses into a ghost-caused seizure and bangs his head on the bedframe. From then on, because of his head injury, Thongsuk is even more off and is consequently bullied by the other kids. Only Nam defends him.
So when Nam (Cheeranat Yusanon), the guys Jack (Acharanat Ariyaritwikol) and Boi (Sean Jindachot) and the lipstick lesbian girlfriends Beam (Busarin Yokpraipan) and Pui (Gitlapat Garasutraiwan) make plans to go to the island without Thongsuk (Chinnawut Intarakusin), Thongsuk schemes to somehow surprise them.
Instead, everyone is surprised, thanks to the evil spirits on the island and Thongsuk being a conduit for them.
What follows is the usual setup of these types of teen-slasher movies in which the hedonistic characters get what's coming to them as they are possessed, picked off or devoured one by one by a mysterious force. Blood and gore fly as grey, smoky CGI baddies haunt the kids. It's like Cabin in the Woods, though less tongue-in-cheek. Backwards-bending characters bring to mind the current Hollywood hit horror Mama.
Nam emerges as the heroine, who must at all costs keep a candle burning to ward off the bad spirits and survive the night.
Of course there's a red herring or two to put you and Nam off the scent. Let's just say if you're in a horror movie and Wonderful Town's Anchalee Saisoontorn turns up as your mother, you might not want to trust her.
Overall, its actually not bad. You should check it out.