Liam Neeson and his wife, Natasha Richardson, who died in a skiing accident last March, will appear on the big screen together in a documentary about the life and works of British explorer George Mallory this summer.

The documentary, "The Wildest Dream," tells the tale of Mallory's two greatest loves, his wife Ruth and his obsession with the "last great adventure."

Mallory set out to become the first ever person to climb Mount Everest, the worlds highest peak.

Ruth Mallory is voiced by Natasha Richardson in her final role before she was killed in a skiing accident in Canada last year.

Throughout the film, Richardson's voice can be heard through love letters she had written her husband while he is on expedition.

Neeson narrates the film which is due to be released in August.

Mallory (voiced of Ralph Fiennes) was last seen alive 800 ft from top of the summit. He disappeared shortly after in 1924. Conrad Anker, also featured in the film, found Mallory's remains frozen in 1999.

In 2007, Anker returned to Everest to retrace Mallory's steps. He used clothing from the 1920s and equipment that Mallory would have used. Anker set out to solve the mystery of whether Mallory succeeded in reaching the summit.

The director Anthony Geffen said: “Mallory fascinates me because he dared to dream the impossible. In a golden age of exploration, he was the pioneering adventurer determined to reach into the world’s last great, untouched wilderness. The Mallory story is still as tantalizing and compelling today as it was in 1924.”

Mallory is famously quoted as having replied to the question "Why do you want to climb Mount Everest?" with the answer: "Because it's there."

The documentary is dedicated to Richardson.