Lucky Starr and the Rings of Saturn
Isaac Asimov
 Six weeks after returning from the Jovian system, David "Lucky" Starr learns that Jack Dorrance, the chief of a Sirian spy ring uncovered by Starr in the Jovian system, has escaped from Earth. Starr and his sidekick Bigman Jones follow Dorrance to the Saturnian system, where Dorrance tries to lose them in Saturn's rings, but his ship is destroyed by a ring fragment. A Sirian ship then contacts Starr and informs him that the Sirians have built a colony on Titan and claimed it for Sirius, contrary to established precedent that all worlds in an inhabited stellar system belong to that system's inhabitants, whether they have permanent settlements on those worlds or not. Starr orders the pursuing Terrestrial fleet back to Earth; but returns with Bigman and Councilman Ben Wessilewsky to the Saturnian system. When several Sirian ships pursue the Shooting Starr, Starr conceals himself and his ship in the interior of Mimas; leaves Wessilewsky below the surface with enough supplies to maintain himself for several months; then takes the Shooting Starr back into space, where they are captured by the Sirians and taken to the colony on Titan. There, Sirian commander Sten Devoure threatens to have Bigman killed unless Starr agrees to testify at an upcoming interstellar conference on the asteroid Vesta that he entered the Saturnian system to attack the Sirians. When Bigman endangers himself by defeating Devoure in a duel, Starr makes a deal with Devoure: if he spares Bigman's life, Starr will testify that he entered the Saturnian system in an armed ship, and will lead the Sirians to Wessilewsky's base on Mimas. At the Vesta conference, Devoure admits that the Sirians have established a base on Titan, but insists that the fact that Saturn and its moons are part of Earth's stellar system is irrelevant: "An empty world is an empty world, regardless of the particular route it travels through space. We colonized it first and it is ours". Devoure then brings out Starr, who admits to having re-entered the Saturnian system after being warned off, and also that Wessilewsky established a base on Mimas. When asked his reasons, according to a secret plan of his own, Starr replies that Wessilewsky was placed to establish a colony on Mimas; whereupon Conway states that by removing Wessilewsky from Mimas, the Sirians violated the very principle they attempted to establish. The conference ends with three client worlds voting with the Sirians, and the rest voting with Earth, with the result that the Sirians are ordered to leave Titan within a month.