George MacKay & Dean-Charles Chapman Step Out For '1917' Screening in San Francisco

George MacKay and Dean-Charles Chapman step out for a special screening of their new movie, 1917, during SSFILM at the Castro Theatre on Thursday night (December 12) in San Francisco, Calif.

The two stars were joined by writer Krysty Wilson-Cairns, and director Sam Mendes for the event.

PHOTOS: Check out the latest pics of George MacKay

“The idea was loosely based on a story my grandfather told me,’ Sam shared about the movie to Deadline. “The movie is dedicated to him…”

He added that George and Dean-Charles‘ characters are not him, but are in “the spirit of what he told me and the central idea of a man carrying a message wouldn’t leave me. It just clung on in there somehow, for the last 50 years.”

1917 opens on Christmas Day.