The Canal (2014) is one of those films with an ending that nobody saw coming. It’s a “ghost in the house” story that may or may not have any ghosts, and follows the downward spiral of a man versus his family. The film’s ending not only slaps you in the mouth with a sack of rocks, it makes you reconsider everything you’ve just watched. But the film is deliberately constructed to be ambiguous, so there’s no concrete answer as to what happened at the end.

Early in the film, David (Rupert Evans) sees video footage that shows satanic rituals being performed in his house over 100 years earlier. He learns a family lived there until the husband went crazy and killed his wife in the room that now serves as David’s bedroom. Around the same time David sees this footage, he discovers that his own wife, Alice (Hannah Hoekstra), is cheating on him with a work colleague. Alice soon goes missing. After her corpse is discovered floating in the canal near their home, David is naturally the prime suspect. As the dyspeptic police detective tasked with the investigation tells David, “Do you know why people always suspect the husband? Because it’s always the husband. Every fucking time.”

The night of Alice’s murder coincides with David’s encountering a nightmarish demonic figure in the world’s most disgusting public toilet, creating a haziness of that night’s chain of events both for him and the viewer. As the demonic presence grows richer throughout the film’s story, the audience spends its time wondering if demons are truly at work, or if David is losing his mind and he actually did murder his wife.

The ending takes David into the depths underneath the canal, carrying his son, Billy (Calum Heath). David sees the decomposing body of his dead wife down there, giving birth to a dead baby (she was pregnant when murdered). David finds himself with his son under the canal’s water, where he’s held under by his dead wife as his son floats to safety. In the next scene, Billy is in the custody of his grandmother who is putting the house up for sale. Billy goes inside to get his dinosaur book when a voice from behind the wall, which claims to be his father, says the family can be together again. We then see Billy toss himself out of his grandmother’s moving car. It’s rough.

In the final shot, the house’s realtor sees Billy (after his suicide) closing the bedroom door at the top of the stairs. She smiles at him. Wait. What?

Two major conclusions about what happened during this film’s ending can be reached: One, the house was possessed by evil spirits from the actions that took place there in 1902, which caused David to go insane. It took the form of his murdered wife in the canal to murder him, then took the form of David himself to “murder” the son.

The alternative is that everything was a construct of David’s mind, seeing as he lived in the house for five years without issue. It wasn’t until he saw the footage of his house’s history and learned of his wife’s infidelity that everything got out of hand, supporting the idea that it was all a projection of David’s inner downward spiral. The vision in the cracked wall at the end was Billy’s own psychosis, which he developed thanks to the trauma he experienced after his parents’ deaths. The second scenario, however, doesn’t rule out the possibility that malevolent forces in the house still contributed to David’s mental deterioration.

In either interpretation, the final shot of the realtor smiling at ghost Billy is still mysterious. It seems to imply she believes the house is haunted, as if she isn’t surprised to see him standing there at all. How we read that ambiguous moment depends on which interpretation we choose for the overall story.