Firewatch

In the spring of 1989, after his wife Julia (Larissa Gallagher) develops early-onset dementia, Henry (Rich Sommer) takes a job as a fire lookout in Shoshone National Forest in Wyoming. On his first day, Delilah (Cissy Jones), a lookout in another watchtower, contacts him via walkie-talkie and asks him to investigate illegal fireworks by the lake. Henry discovers a pair of teenage girls, who accuse him of leering. On his way back to his tower, he comes across a locked cave and spots a shadowy figure watching him. He returns to his watchtower to find it ransacked. The next day, Delilah asks Henry to investigate a downed communication line, which he finds cut. Henry and Delilah plot to scare the teenage girls off, but Henry finds their campsite ransacked and abandoned. The teens are reported missing; fearing an inquiry, Delilah falsely reports neither she nor Henry encountered the girls.
While out hiking, Henry finds an old backpack and a disposable camera belonging to a boy named Brian Goodwin, who was the son of former lookout Ned (Mac Brandt). Ned was an outdoorsman who drank heavily due to traumatic experiences in the Vietnam War, while Brian enjoyed fantasy novels and role-playing games. Though it is against the rules for employees to bring their children to the towers, Delilah was fond of Brian and lied about his presence. He and Ned apparently left abruptly and never returned.
A few months later, a small wildfire breaks out south of Henry's tower. Henry discovers a radio and a clipboard while fishing, with notes including transcripts of his conversations with Delilah. He is knocked unconscious by an unseen assailant and wakes up to find the clipboard and radio gone. In a nearby meadow, Henry finds a fenced-off government research area. He breaks in and discovers surveillance equipment and typewritten reports detailing his and Delilah's conversations and private lives. He also discovers a tracking device and takes it with him. Disturbed by this discovery, Henry and Delilah discuss destroying the government camp but decide against it. However, as Henry hikes home, someone sets fire to the camp.
The next day, Henry uses the tracking device to find a backpack with a key to the locked cave. Delilah reports a figure in Henry's tower; when Henry arrives, he finds a Walkman taped to the door with an incriminating recording of Henry and Delilah's discussion about destroying the government camp. The next day, someone impersonating Henry calls another lookout and claims Delilah knows the cause of the camp fire, putting her and Henry more on edge.
Henry uses the found key to enter the cave but is locked inside. Heading deeper into the cave, Henry discovers the decayed body of Brian Goodwin. Henry finds a way to the surface and reports Brian's death to Delilah, who is upset by the news. The next day, an evacuation order is given for all the lookouts, as the wildfire has grown out of control.
As Henry prepares to leave, the tracking device begins beeping. He follows the signal and discovers a tape recorded by Ned Goodwin, who has been the figure watching Henry. Ned claims Brian's death was accidental and that the boy fell due to climbing inexperience. Unwilling to return to society after Brian's death, Ned secretly lived in the area ever since. Choosing to venture deeper into the wilderness, Ned warns Henry not to look for him.
Henry finds Ned's camp filled with items stolen from the government camp, the lookout towers, and the teenage girls, who Delilah confirms have been found safe. The government camp was simply studying wildlife; Ned created and placed transcripts there to scare Henry away. Delilah blames Ned for Brian's death and leaves on the rescue helicopter. Henry goes to her tower, and he and Delilah say their goodbyes via radio before Henry evacuates.