Emily Cass McDonnell in “The Thin Place” | Photo by Jonathan Roberts

The Humana Festival of New American Plays continues with the premiere of Lucas Hnath’s “The Thin Place.”

Hnath is a frequent visitor to Louisville, having premiered plays at a couple of Humana Fests. He’s a repeat collaborator with Les Waters, and we have seen his work once already this season in “A Doll’s House, Part 2.”

With “The Thin Place,” he’s presenting tricky and challenging work that masquerades as a showy and spectacle-oriented ghost story. It’s easy to miss what lies beneath, and one suspects that’s kind of the point.

The play centers around Hilda (Emily Cass McDonnell) and her friendship with Linda (Robin Bartlett). Hilda believes in ghosts, as she explains in the first few moments of the play. Linda is a medium who talks to spirits, and I’ll leave it up to you to figure out whether or not she’s a true believer.

Kelly McAndrew and Robin Bartlett | Photo by Jonathan Roberts

They are joined by Jerry (Triney Sandoval) and Sylvia (Kelly McAndrew), friends of Linda’s who become friends of Hilda’s — sort of.

The structure of this thing is a marvel, stacking conventions and conceits one upon another in a way that manages to feel organic and real.

The play breaks the fourth wall, possibly invites audience participation, has stories within stories, and specifically invokes the old traditions of telling ghost stories at parties.

And that’s before you get to the stage tricks that hearken back to a time before CGI and million-dollar stage illusions.

Hilda directly addresses the audience, which is heightened as the play starts with the house lights left on at full power, leaving us naked to Hilda’s piercing and discomforting gaze.

That moment when the audience realizes the lights are going to stay up is just a taste of the way light will be used throughout the play. It gives lighting designer Reza Behjat a time to shine.

McDonnell’s Hilda is a constant and unsettling presence. Her affect is almost flat, with an occasional dip into a kind of self-effacing yet sinister smirking humor. Pretty much immediately the audience gets the feeling she is not to be trusted, a feeling that is frequently reinforced with uncomfortable throwaway lines that are tossed out and forgotten so fast that one almost doubts they happened at all.

Bartlett’s Linda is equally unsettling, but she accomplishes it by moving to the opposite side of the spectrum. She’s too comforting, too kind. Anyone who’s spent anytime around real narcissism will recognize her behavior and know immediately that she is not to be trusted.

But maybe she is to be trusted? When we’re talking about different layers of reality and the supernatural, easy answers about the pathology and personalities of the natural world come under scrutiny in a way that marries theme with format, genre and story. That’s a neat trick — and basically the whole reason magical realism exists in the first place.

There is a maternal aspect to Hilda and Linda’s interactions, which is an open door into the themes of how we lie to the ones we love and manipulate the people who trust us.

Despite the many layers of discomfort the audience will feel, Hnath skillfully inter-cuts moments of comedy throughout the majority of the play. It manages to simultaneously lighten the mood and make the suspense more intense.

When will the laughter stop and let the discomfort return in full force?

The cast of “The Thin Place” | Photo by Jonathan Roberts

The piece allows showy flourishes from the actors, the designers and Hnath’s  script, but director Les Waters steps out of the way, skillfully leading the actors through difficult tone changes and emotional moments.

My personal theory about theater is that if it is to survive, it must present work that can only be accomplished on stage with a live audience.

Hnath is using and subverting the conventions of theater in a way that is delightful and uniquely theatrical. It’s easy to just sit back and enjoy a ghost story and a gripping piece of storytelling.

But I suspect the content that is hidden beneath Hnath’s clever games will come back to you, perhaps at a subconscious level, when you are lying in the dark and remembering your own ghosts.

“The Thin Place” continues as part of the Humana Festival of New American Plays through April 7. Actors Theatre is located at 316 W. Main St.

Insider’s reviews of the 43rd annual Humana Festival: