Warning: This post contains spoilers for episode 4 of True Detective: Night Country.

After the third episode of True Detective: Night Country ended with Navarro (Kali Reis) having a vision of a zombie-like version of surviving Tsalal scientist Anders Lund (Þorsteinn Bachmann) delivering a message from her late mother before flatlining at the hospital, episode 4 only ramped up the story’s seemingly supernatural elements.

In some ways, this seems like a departure from the series’ previous seasons, in which supernatural undertones could largely be explained away by plot points that were grounded in reality. In Season 1, Rust Cohle’s (Matthew McConaughey) hallucinations—despite sometimes appearing to relate to the case—were attributed to his years of drug use while working as an undercover narcotics officer. In Night Country, the ghosts of the past are a bit more literal. But that doesn’t mean they’re beyond a reasonable explanation.

As episode 4 progresses, we gain more insight into Navarro’s state of mind—especially in the wake of her sister Jules’ (Aka Niviâna) suicide. Although Jules was the one who openly struggled with what Navarro says was schizophrenia, bipolar disorder, and borderline personality disorder, it seems to be becoming more apparent that Navarro may have some mental health issues of her own. Navarro and Jules’ conversations indicated that Jules had been exhibiting similar behavior to their mother, who Navarro has said was murdered by an unknown assailant. Given her genetic history, family trauma, and apparent PTSD from multiple military tours, it wouldn’t be surprising if the strange things Navarro has been seeing are hallucinations like her mom and sister experienced.

Read more: What to Know About the Mysterious Spiral Symbol in Episode 2 of True Detective: Night Country

Danvers (Jodie Foster) also says that Navarro saw “a ghost or some kind of spirit” in the room when they went to the home of serial abuser William Wheeler (Kasper Leisner) after he murdered his wife—the final case they worked together. Navarro denies this claim, but admits that she believes her mother and sister were cursed—and that she is as well. “It takes us one by one. And you know who’s next,” she says. “Something calls us and we follow. And it’s calling me now.”

Of course, if everything happening to Navarro is actually in her head, that still doesn’t explain how Rose Aguineau (Fiona Shaw) was led to the bodies of the Tsalal scientists by the ghost of her dead lover Travis (Erling Eliasson)—or some of the other spooky sequences that have occurred.

One clue as to what’s really going on could be what Rose told Navarro in episode 2: “Don’t confuse the spirit world with mental health issues.”

This comment was in reference to Jules, but could be applied more broadly to what we’ve seen play out in Ennis as the town has been plunged into polar night. Showrunner Issa López has also offered some insight on her outlook on the seemingly supernatural. In an interview with the Los Angeles Times, she spoke about how a lack of closure surrounding the death of a loved one can deeply affect your psyche.

“You have this feeling, even if you know rationally that this person is dead and gone, a part of you is kind of expecting to find them around the corner throughout your entire life,” she said. “And I think that informs my storytelling—the sensation of the sudden loss of someone who is the center of your life is very much the story in [my film] Tigers [Are Not Afraid] and is very much the story of True Detective.”