The play is set in 1985, on Siula Grande in the Peruvian Andes. It follows Joe Simpson and Simon Yates as they climb the west face of the Siula Grande, becoming the first climbers to reach the summit using the west face. Descending down the north ridge tragedy struck as Simpson slipped down an ice cliff, breaking his right leg. With Simpson incapacitated Yates lowered Simpson off the North Ridge by tying two 150-foot lengths of rope together to make one rope. With worsening conditions, frost bite and complications with the knots Yates inadvertently lowered Simpson off a cliff and Simpson accidentally dropped one of the cords required to ascend the rope.