The night before Alex Honnold would try climbing the 3,000-foot granite wall known as El Capitan without any ropes or other safety gear, his film crew was ready for the worst.
"We had protocol about what would happen, what we would do if he fell," said filmmaker Jimmy Chin. "I mean, we had two press releases the night before. One if he made it and one if he didn't."
On June 3, 2017, Honnold made his way to the top in 3 hours, 56 minutes, and became the first person ever to climb the Yosemite National Park wall without any safety gear — just shoes and a chalk bag to help keep his hands dry. It's known as free-soloing in the climbing world.
Honnold's historic feat and the two years of training before it are captured in the new movie "Free Solo," whose run at Minneapolis' Lagoon Theater has been extended because it's so popular.
Chin, a Mankato, Minn., native and one of the lead filmmakers, has been friends with Honnold for years.
In setting the terms for how to film such a dangerous feat, Chin said he made it clear to the rest of the crew and National Geographic that Honnold's safety and climbing experience would always take priority over the filming.
"If there was any moment where Alex felt like the risk was too high with the film crew, we would not shoot it," Chin told MPR News host Tom Crann.
It takes a unique skill set to get on a team tasked with filming a climb like this.
Chin's first criterion to work on what would become "Free Solo": be a professional climber.
The second criterion is to be an "incredible" cinematographer. "Which brings the pool down to about three or four people on the entire planet," Chin said.
Even after the crew was ready to film, it was always uncertain whether Honnold would attempt the climb.
"We carried a pretty heavy burden for two years not actually knowing if the event was ever going to happen," Chin said.
The film wouldn't have happened without high levels of trust among Honnold and the camera crew, Chin said.
Many of the people who worked on the movie had known and climbed with each other for years.
They filmed two years of Honnold's practice and discussed spots on El Capitan where he didn't want other climbers.
"There were no surprises for Alex," Chin said.
To get around some of the logistical challenges of filming on a nearly flat granite wall with a climber who could not be disturbed, the crew used remote cameras to capture up-close angles of Honnold without causing a distraction.
Honnold even carried a small microphone taped to his chest, with the wire running through his shirt to a receiver zippered in a pocket on his chalk bag.
The combination of gear allowed the filmmakers to show intimate details of Honnold's climb, including the sounds of his breathing.
The moves Honnold makes are only possible for world-class climbers. Honnold even fell on some of them, while roped in, before attempting the free solo.
"It's literally like an Olympic-level gymnastics floor routine that if you make a single mistake at any moment you would die," Chin said of the climb.
Of course, he made it. Despite all the lead time up to the event, Chin said he was only focused on how to execute the climb. He hadn't thought much about what it'd be like once Honnold reached the top, and said it caught him by surprise.
"We were all very relieved of course," he said. "We were also very happy and proud of Alex."