I know I've seen a fair portion of this film as part of a series on rare silent movies, which was shown on TV around 25 years ago. It was beautiful and fascinating, and I yearned to see more of it, although most published literature states that it is 'lost'.
As it is extremely unlikely that the film will ever see the light of day in its complete form, a spoiler warning is irrelevant, and the following is gleaned from published synopses more than from my personal recollection.
It is an early space opera, concerning a team of explorers who visit the planet Mars, and encounter a race of peace-loving vegetarians (is there any other kind? Oh, sit down, Adolph!). They return to Earth with the high priest's lovely daughter, and the plea for peace is threatened only by one villain who is dealt with by what can only be described as an Act of God.
Apart from George Melies' crazy moon explorer fantasies, this seems to be the first interplanetary adventure film in history, and from a country (Denmark) not noted for science-fiction films of any kind. Maybe they thought that they'd never do one better than this.
We might giggle at the idea that the spaceship had propellers on its wings, but come on...we are still accepting lots of logistically improbable and impossible concepts in films of today. I hope this film does still exist somewhere. The fragments I've seen, and the material I've read, makes me yearn to experience the whole of this 90-year-old space opera.