This is a movie that was made within the last 10-20 years. I’m decently sure that it was set in Spain, Brazil, or another primarily Spanish or Portuguese-speaking country. The main character is a tourist that’s implied to be escaping his past back in his home country, most likely the United States. It’s later revealed that the main character was unable to save his brother from drowning, and it haunts him.
I believe the tourist was found by the love interest doing something like sleeping in a car, likely one he has broken into. The love interest notices this, engages him, and invites him to a party held in a mysterious location.
The tourist attends the party, which might have already been held in some catacombs. The party host initially picks a fight with him, but later invites him to live with his group, who all lives in this catacombs-like location. It develops into a cult, with the party host as a leader. In order to stay living there the tourist has to be initiated, and in the midst of a party he’s given a large dose of drugs.
After being dosed, he continues to have strange visions, of his brother drowning I think. The cult leader continues to lead him through stages of initiation that involve having him feel as if he will be on the brink of death, such as standing in the middle of the road as a group of motorcycles drives through.
It’s revealed that the drug he was dosed with has some sort of dark history in the country tied to mass deaths. He repeatedly visits a man who sells souvenirs, including a book that explains this history. One of the cult members kills themselves. Once the tourist starts getting suspicious of the cult leader’s plans, he murdered the shopkeeper for explaining it to him. There’s also a subplot about a local asylum in which one of the children killed all of the workers and released the other children, or something similar.
The big plot twist is that the tourist and the cult leader were two of the children in that asylum, and either the tourist and the cult leader was the murderer. The murders apparently occurred after they were being experimented on using the drug the tourist was dosed with before, and had something to do with psychic powers I think?
Sorry for the long post, but I remember a lot of the details about the movie, but can’t seem to find it anywhere. I might be wrong about some of these details, and that’s why I can’t. I’d love it if you were able to help!