Season 1
In 1999, Dan's in grade eleven when he transfers to Saint Lawrence’s, an all-boys catholic school. His father is being treated at a nearby hospital for end-stage brain cancer; his mother died when he was only seven. Dan is close to Brother Anurak, the school's dean and a psychologist. Brother Anurak tries to cure Dan of his sleep paralysis. In his dreams, Dan sees a shadow that suffocates him and it only gets worse when he transfers. Dan causes a panic on his first day when he chooses a seat at the desk of Trin, a senior who mysteriously vanished at the lake behind the school a year prior. No one dares to sit at that desk, and no one dares throw it away. He gets to know his classmate Nine and roommate George as well as Cha-em, a student from Saint Mary's who comes to perform in the annual play. As the four of them grow closer, they begin to look into Trin's disappearance while helping Dan evade the shadow that's plaguing him.
The Lake
Dan sits in Trins spot, and other students start spreading rumors about Trin's disappearance.
Nai
Dan gets closer to Nai, and he learns why Nai gets bullied at school.
The School Play
Nai brings Dan to a monk for help, and the monk gives Dan a method of dealing with the shadow.
Chess
Dealing with the fact that his father is about to pass, Dan recalls his sad family history.
Trin
As it's been almost a year since Trin's disappearance, Dan and Nai start to investigate the reasons behind it.
Funhouse
Cha-em is extremely kind to Dan, which Nai and Josh aren't too happy about.
One Armed Man
Dan accidentally loses the ring the monk gave him, and he starts having trouble distinguishing his dreams from reality.
Dream Journal
Dan and Nai start to look into Trin's treatment history and recordings in order to uncover the truth.
A Shaman in the Forest
Josh brings Nai to look for someone else who can help them out, while Nai asks the temple monk to figure out a way to protect Dan.
School Night Party
Dan and Nai along with others conspire to reveal the school's hidden truth at the school party.
Payback
Anan makes trouble for Dan and Nai, but he didn't expect the shadow to suddenly appear and protect Dan.
Hamlet
Dan disappears without a trace and everyone is unable to find him, which puts the school play in jeopardy.
Third Eye Shut
Dan and Chaaim are both in comas; Nai remembers something Dan once said which proves to be the key to solving a puzzle.
Where is Dan?
Nai and Teacher Anurak try every possible method to bring Dan back from the other side.