Best friends Becky Connor and Shiloh Hunter are climbing a mountain with Becky's husband Dan, who is startled by a bat and falls to his death. A year later, Becky has given up climbing and become a recluse contemplating suicide. She has estranged herself from her father James, because he thinks Dan would not have grieved as she has if the situation were reversed. Just before the anniversary of Dan's death, Shiloh invites Becky to climb the decommissioned B-67 TV Tower in the desert before it is demolished. Shiloh suggests she scatter Dan's ashes from the top as a form of healing. A reluctant Becky accepts, hoping to finally move on from Dan's death. The next day, Shiloh and Becky arrive and climb several severely corroded ladders to a tiny platform at the top of the tower, where Shiloh goads Becky into momentarily free-hanging off the platform, while Shiloh records for her YouTube channel. Becky scatters Dan's ashes. As the two begin their descent, the ladder breaks. Becky falls but is caught by a rope connecting her to Shiloh. Shiloh pulls Becky back up and they realize they are now stranded hundreds of feet above the next intact ladder, at a height of almost two thousand feet above the ground. Becky's thigh has also been cut. Their backpack with their water and a small
quadcopter drone falls onto a
communications dish below them. Despite the remote location, Shiloh is confident that someone heard the crash of the ladder, but help does not arrive. They try to use their cellphones, but
radio interference from the communications dish blocks the signal. Shiloh sends a message for help to her Instagram followers by packing her phone in a shoe and dropping it outside the range of the interference. The pair notice a man and his dog but cannot get his attention. The man joins another man camping in an RV nearby. They wait till night and use a
flare gun found in an emergency box on the platform to alert the men. The men see the flare, but they steal Shiloh's car and drive off. The pair realize Shiloh's phone dropped in the shoe must have been smashed as still no help has come. Becky notices a tattoo on Shiloh's ankle: "1-4-3", a code Dan used to say "I love you" to Becky. Shiloh tearfully admits to a four-month affair that ended before Becky and Dan's wedding. The next day, Shiloh climbs down using the rope to retrieve the backpack with water but nearly falls. Shiloh injures her hands but successfully ties the rope to the bag, and Becky uses all her strength to pull both Shiloh and the backpack up. Becky has a nightmare of a vulture eating Shiloh's dead body. Becky uses power from the tower's
aviation obstruction lighting warning light to charge the drone, whilst being attacked by a vulture, and sends the drone to a nearby motel with a written message for help, but the drone is struck by a truck and destroyed. Becky is
delirious from dehydration, but in a brief lucid moment, she realizes Shiloh fell onto one of the communication dishes when retrieving the backpack and died; Becky has been hallucinating her presence since then. The next day, Becky is awakened by a vulture gnawing at her wounded leg; she kills the vulture and eats it. Her strength partially restored, she
abseils down to the dish where Shiloh's body lies. Becky types a text message to her father on a second phone, then puts it in Shiloh's shoe and shoves them into Shiloh's body before pushing the body off the tower. Shiloh's body cushions the impact and the message transmits. James alerts emergency services, who then rush to the tower. Becky and James reunite and reconcile. ==Cast==