Lost in La Mancha

Lost in La Mancha is a 2002 documentary film about Terry Gilliam's first attempt to make The Man Who Killed Don Quixote, a film adaptation of the 1605/1615 novel Don Quixote by Miguel de Cervantes. The documentary was shot in 2000 during pre-production and filming and it was intended as a "making-of" documentary for the film. However, Gilliam's failure to complete his film resulted in the documentary filmmakers retitling their work as Lost in la Mancha and releasing it independently.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.