Extraterrestrial intelligences operate on Earth undetected by the public. The largest, worldwide security service Life-Int-Ltd. becomes aware of this. Sigurd Westall, a new employee of the corporation, is sent to investigate the aliens right after his basic training. No one, except his immediate superior, knows that he has had a special ability since puberty. He is assigned to a team of specialists who set out to track down the aliens. When it comes to direct confrontation, it is only thanks to this ability that he survives.
Together with the female spaceship Paurusheya, Sigurd Westall reaches Saturn's moon Japetus. There he finds a huge lunar station embedded in the ridge at the edge of the dark hemisphere. The station is also the destination of the strangers in the small spaceship he is pursuing. Sigurd initially tries to find his two abducted colleagues on his own. But when he is quickly discovered by the aliens, he is forced to defend himself. In doing so, he gets help from a side that plunges him into a personal crisis in the course of the further plot.
