Thinking he's satisfied with running his retirement business as a hunting guide in the high, snowy mountains of Reno Bright—a planet well off the main roads of commerce in the Fellowship of Humanity—Rennie Mikovich isn't looking for a job. But when a mysterious stranger named Maki Honamatsu offers him a berth as astrogator on a mission to a distant and unknown star system, Rennie signs on.
What he finds on Thendara, one of Reno Bright's moons, is a salvaged and modified alien starship. In short order, he meets the young, cute, tough-talking pilot, Karla Formanti, and then the rest of the crew. The Captain, Jahn Prudeaux, is a man used to giving orders, and having them obeyed. Rennie can live with this but he doesn't trust Prudeaux's motives. The ship's engineer, Leta Niemeroff, is also the Captain's mistress. The ship's nanotech specialist, Nikolas Omstead, takes an immediate dislike to Rennie, and isn't shy about his feelings.
When Rennie asks about the objectives of the mission, he gets half-answers and incomplete information. When he asks about the origin of the ship, he gets lies. When the ship flies, he gets a shocking introduction to the way other beings solved the problem of faster-than-light travel.
Once their ship makes the first planetfall, Rennie begins to understand the scope of the lies he's being told. As members of the crew plunder a building in hope of finding the secret to manufacturing the FTL engine in their ship, they meet failure, and then armed resistance. In the ensuing melee, Maki Honamatsu is killed and Captain Prudeaux is badly wounded. Rennie manages to save the day through forceful action, and what's left of the crew escapes into space.
Prudeaux and his crew haven't found what they want, so they tell Rennie they are continuing the mission. He tries to talk them out of their plans, but when he can't, goes along with their agenda. On a planet in a different star system, Prudeaux and his crew find the secret of the FTL drive, but again, they meet with resistance, and in the ensuing firefight, get separated.
Rennie and Karla Formanti locate Prudeaux and Leta Niemeroff and set of on a rescue mission. The operation is a partial success, because only Nimeroff is still alive, but greviously wounded. Nikolas Omstead may still be alive, but is among the missing.
When Rennie and Karla take Niemeroff back to the lander for medical treatment, Omstead is waiting for them. He tells Karla that he is going to get rid of Rennie, and Karla identifies herself as an undercover Fellowship officer and tries to place Omstead under arrest. He shoots her, and Rennie shoots him, killing him instantly.
Rennie places Leta Niemeroff and Karla Formanti in autodocs, and engages in the horribly difficult job of piloting and navigating the unfamiliar ship back to Reno Bright. Both women are seriously wounded, and Rennie wonders if either will survive long enough to reach their destination.
As they approach Reno Bright, Rennie knows that the ship is far more trouble that it's worth, that, indeed, knowledge of its presence might precipitate an interstellar war. As he struggles with decisions, Leta dies. Rennie decides to take Karla, in the autodoc, and a flash-frozen Leta back to his lodge on Reno Bright in the lander. He will sacrifice the star ship by using autopilot to crash it into the airless moon, Thendara.
After a disastrous landing, Rennie manages to get Karla back to his lodge without being spotted. He then cremates Leta's remains, scatters her ashes, and over what's left of a long winter, he nurses Karla back to health. As the spring comes, she tells Rennie that she has to report back to Fellowship HQ on Reno Bright. As she prepares to leave, he asks if she will tell her bosses about him. She assures him his secret is safe, but won't promise to return. He can only hope that she will.