The deeper you get into YOU LET ME IN, the debut novel from Norwegian writer Camilla Bruce, the more lost you’re apt to come.

This is very much by design. From almost the first paragraph of her novel, Bruce does her level best to keep her reader off-balance, gently lulling them through what seems like a standard whodunnit murder mystery into a world where simple questions like, “What happened?” are matters of opinion. I’ve read the novel twice now, and both times I walked away convinced of different things entirely.

That would no doubt be Bruce’s point. YOU LET ME IN is a work that asks us to confront our ideas of perception and insanity. Its narrator, fallen romance novelist Cassandra Tipp, is either telling the total truth or has been silently suffering from any one of a number of schizoaffective disorders for her entire life. And while the tale she tells is, either way, a twisted, bloody nightmare, it’s that kernel of doubt, which permeates the entire novel, that provides the true horror.

In one version of her story, she has suffered all her life from the presence of a malevolent fae creature she calls Pepper-Man, who claims to have bonded with her as a baby and cannot leave her side for long and who commits acts of atrocity to protect his human bond. In another version, Tipp suffered a psychotic break after years of abuse and created Pepper-Man as a way to block her mind from experiencing the horror she’s caused.

Basic though that sounds, Bruce does a remarkable job balancing the conflicting realities that pull her story along, forcing the reader to question themselves repeatedly throughout the process. Somehow, whether you take it as a dark, Guillermo Del Toro-esque fairy tale or Shirley Jackson-esque musing on mental health, Bruce manages to infuse the tale with darkly twisted imaginings.

Written as a confessional, YOU LET ME IN revels in its tragedy, which gets deeper depending on which way you read the book. As soon as you feel you have a bead on the story, Bruce throws you another curve and completely upends your theory while giving you something else to consider. All the while, you’re forced to wonder what is sanity? How can we believe the things Cassandra tells us about Pepper-Man and the various malevolent fae who exist in his circle? On the other hand, how can we not?

While I can answer neither of those questions, I can tell you that asking them for myself while reading the book made YOU LET ME IN a fascinating work to dissect and consider. On top of that, Bruce writes with pointed, eerie prose, like the whispers of the creature standing in a darkened corner of your bedroom. A slim volume, Bruce still manages to pack in a heavy experience that belies its status as a first novel.

What Bruce and her novel deal best in, ultimately, is the unknown. What we don’t know and can’t know colors the edges of all our perceptions, forcing us to trust the bonds of common reality to hold us all together. What if those bonds are illusions or what if we lose sight of them? The line that separates sane and insane, reality and imagination, has always been thin. Thinner, perhaps, than any of us are comfortable with. It’s on that line where Bruce writes, and on which side you sit is always up for debate.

Camilla Bruce’s YOU LET ME IN is now available in the United States.