The Ghost in the Swamp (2006)

After Liptus arrives in a small village from the city, he calls his best friends, Miron and Melita, on winter holidays in Kopacevo. That same night, while they are all sleeping cozily, from their deep sleep Miron and Melita are woken by the disturbing sounds of villagers, carrying flares and disappearing into the darkness at the end of the street. At the docks, they find Halasz, a boy known for his bravery. He is cold, pale from shock, and babbling a white ghost. While most of the villagers don't believe Halasz's story, older citizens recall a long time ago when a forgotten spirit would scare people at night in dark and foggy swamps. Everyone locks themselves in their houses and Halasz ends up in a hospital where the doctors can't help him. Miron, Liptus, and Melita, now alone, take matters into their own hands, revealing the secret of the ghost and saving their friend.

Unfortunately the movie The Ghost in the Swamp is not yet available on HBO Max.