This weekend and next, the theater department at Vashon High School will clear up some mysteries and secrets that have lately tantalized Vashon.

Stephen Gregg’s documentary horror play, “Trap,” takes viewers into a theater with a traumatic history, culminating in a show that is meant to surprise and strike its audience.

“The less you know about the play, the better,” said Andy James, the show’s director. “This is a rare experience that you cannot predict, and a show full of experiences you may never have had in the theater.”

As a starting point, the play begins by telling the story of a performance in a California theater at which all the audience members fell unconscious. Working in the documentary style of “The Laramie Project” and “Twilight: Los Angeles,” the show retraces the steps of an investigator (played by Ella Saffery) and a firefighter (played by Henry Sutherland) who race to find out what happened.

“Without giving anything away, I can say that the boundary between this world and that one becomes very thin,” James said.

James notes that the show creates a sense of continuous threat, through means that may prove unsettling to some.

“It’s meant to cause you a bit of distress. Audiences have been known to scream,” James says, adding that children may find it all a bit too much.

The lead-up to the show has involved some enigmatic roadside posters and postings to social media, all part of a game the troupe promises will be advanced in the show itself.

The excitement about promotional shenanigans mirrors the whole cast’s determination to create a powerful and one-of-a-kind theatrical experience.

“I have never, ever had a cast react as this one did at the end of our first reading,” James says. “They were freaking out with excitement.”

The cast of 22 students includes many students who are new to the program, as well as a few veteran performers audiences will recognize from recent VHS productions of “The Mousetrap” or “As You Like It,” among others.

Tickets are $12, or $10 for students and seniors.

The show runs this weekend, at 7 p.m. on Friday and Saturday, Nov. 15 and 16, with a 2 p.m. matinee on Sunday, Nov. 17. The second weekend starts with a 3:30 matinee on Thursday, Nov. 21, and 7 p.m. shows on Friday and Saturday, Nov. 22 and 23.

To buy tickets online, visit the program’s website at tinyurl.com/3hyuthfn.

Correction: A previous version of this article referred to the play’s title as “The Trap.” The title is simply “Trap.” We regret the error.