The book takes place on board an intergalactic reconnaissance ship. Five galaxies have been explored and populated. Humanity maintains contact with some races and is at war with others. The exploration of the Sixth Galaxy is underway. As an experiment, a ship with an experimental crew is sent to the insignificant, uninteresting, small galaxy of Noran. All crew members, with the exception of the pilot, are close relatives. While flying in intergalactic space, the pilot suddenly discovers the presence of a real elf. In ancient clothes, with a sword on his belt, the blade of which is made of a solid ruby. The crew is trying to find the answer to the questions of who this elf is and how he got on their ship. Two more surprises await them on the way: less surprising, but much more terrible... Will the ship reach its destination, and will the Tarns find out who this mysterious elf is?