The navy captain Avanti Planetaros is inspired by his astronomer-father to travel through outer space to reach other worlds. He becomes an aviator and, along with the young scientist Dr. Krafft, the driving force behind the construction of a space-ship. Despite oppostion from the mocking Professor Dubius, Planetaros gathers a crew of fearless men and takes off. During the long voyage, the crew becomes restless; a mutiny is narrowly avoided. Finally, they reach Mars and discover that the planet i...