From Darkness description:

The park ranger, Angelica, seeks the help of her former boyfriend, Viktor, a dog handler, to search for a missing woman in a dangerous nature reserve in Sweden. The search is complicated by a disturbing myth about the Cave Banshee, a vengeful spirit from the Nordic folklore that once lured miners to their deaths in the reserve's treacherous caves. As they delve deeper into the forest, Viktor starts to question his own sanity and whether the rumored Banshee is more than just a myth. To make matters worse, Angelica and Viktor share a painful history with the haunted place. Two years ago, they were unable to locate a child who vanished there during a storm, causing a rift between them that has yet to heal. Viktor must now confront his troubled past and work together with Angelica to survive the night and unravel the mystery behind the woman's disappearance.