Caitríona Balfe is joining Tom Hiddleston and Willem Dafoe in Tenzing, the adventure biopic from Apple Original Films and Oscar-winning The Kings Speech producer See-Saw Films.
US entertainment trade publication Deadline, which first reported Outlander star Balfe's casting, says the film tells the story of "Sherpa Tenzing Norgay and his summit of Mount Everest in 1953 alongside fellow outsider New Zealander Edmund Hillary".
On 29 May 1953, Tenzing and Hillary "defied insurmountable odds" to become the first mountaineers confirmed to have reached the summit.
Loki star Hiddleston will play Hillary and The Lighthouse's Dafoe will play the leader of the expedition, Colonel John Hunt.
Balfe, Deadline says, will play Jill Henderson, "a friend of Tenzing who helped organise trips up Mount Everest".
The role of Tenzing Norgay has yet to be cast.
The film will be directed by Jennifer Peedom, the filmmaker behind the documentaries Mountain and Sherpa, with a script by Oscar nominee Luke Davies (Lion, Life).
"Peedom has a close relationship with the Tenzing family and the Sherpa community following her acclaimed documentary, Sherpa," Deadline adds.
Balfe can currently be seen in cinemas in the espionage thriller The Amateur.
