Getting married can be a pretty terrifying experience. You’ve got to sell your kidneys to pay for it, spend countless hours with people you couldn’t care less about, and then schlep it off to some remote location with your new spouse so he or she can learn all about your disgusting habits and you will have no means of escaping his or her critical stare.

That is Scenario Number One.

Scenario Number Two consists of marrying your best friend and then whisking him away to your family’s cabin for a romantic getaway. There’s only one catch: You’re infected by an alien being living in your womb.

No big deal, right?

Leigh Janiak tackles the tough marriage of romance and horror in Honeymoon, and she does so with a creepy confidence. Newlyweds Bea (Rose Leslie, Game of Thrones) and Paul (Harry Treadaway, Penny Dreadful) are one of those couples: sickeningly sweet and undeniably in love. When they arrive at Bea’s family cabin for the honeymoon, they run into Bea’s old friend, Will, and his wife, Annie.

Paul’s jealousy rears its ugly head and then… things start getting weird. Bea starts forgetting basic information about her life, her old friend has turned into an abusive oddball, and Paul begins to wonder what the hell is going on.

With a cast of four people, Honeymoon relies almost entirely on the leading roles played by Leslie and Treadaway. One or both of them are present in every scene, but their characters never seem played out. Treadaway pulls the audience through a twisting maze of emotions as he struggles to deal with the fact that his wife is on a rapid decline. Leslie (in a role on the complete opposite end of the spectrum than her portrayal of Ygritte in Game of Thrones) slides from a coy, playful wife to an empty shell with a creepy sense of innocence.

Janiak, who wrote and directed the film, manages to portray the true horrors of uncertainty that come with watching a relationship deteriorate. The tone of the film goes from light and cheerful to damp and pretty damn depressing, the colors and soundtrack melding wonderfully with Paul and Bea’s crumbling marriage.

To be quite honest, I’m not sure the film would have felt as truly constricting had the lead roles been played by anyone other than Leslie and Treadaway. Not only is their chemistry nearly palpable, but the way emotions play out on each actor’s face is extremely difficult to find in horror films. Watching Paul’s heart break as Bea struggles to remember his name… let’s just say I truly felt for the guy.

Honeymoon isn’t one of those jump scare horror movies, but it will definitely creep you out and there are a few choice scenes that had me cringing with just the right amount of gore. This is an undeniably creepy film that will leave you questioning whether or not your partner is truly who they say they are.

Honeymoon will be released through Magnet Releasing in theaters, On Demand, and on iTunes on September 12.