The Vegans realize that there is a dimension portal set up between the worlds. By waiting at its warp point, they send an emissary to the moon who, however, is killed by accident. In an attempt to mediate, Perkins, Hoffmann and Ralph take another trip to the Vega. They fail, and Perkins is captured. A release attempt succeeds, but apparently the commander was brainwashed and remains in a kind of awake coma. Perkins awakes after half a year - at the same time a Vegan spaceship appears on Earth, which is later accidentally shot down (the ship creates an energy field which scrambles electronic processes in both machines and the human body). Vegan survivors try to reach the Dimension Transmitter in order to return to their home world. Professor Common wants to release the Vegans, but the military wants to cross-examine the extraterrestrials. But while transporting them back to the Vega an error occurs, Perkins, Hoffman and the Vegans are hurled not just through space and to the Vega planet, but also into the past, where the two humans witness the accidental death of a nobleman and are blamed for murder. At the last second, Professor Common finds the two men and can bring them back.