Chekov is aboard a shuttle making deliveries of emergency supplies, when the craft crashes in a water-filled crater. He gets all of the crew safely to the shore, but one of them is killed by someone with a projectile weapon and Chekov gets injured. They succeed in making their way back to a nearby town after getting assistance from a former Starfleet officer, Gwen Thee, who is now breeding dogs and other animals for the settlers. Meanwhile, Sulu and Uhura, along with a couple of scientists, set out to search for the downed shuttle (the Enterprise is off protecting the area against pirates) and they discover some serious flooding near where the shuttle was believed to have crashed. They are initially warned that a group known as the Carsons are causing trouble in the area and the local town has a security force known as the Peacemakers, but it soon becomes apparent that the Peacemakers are the real problem. Sulu meets up with the Carsons when they come to warn him about the Peacemakers, but Uhura gets captured by the Peacemakers. The Peacemakers, led by the local sheriff, Serafini, and the Chief Technical Officer, Bartels, have been illegally mining olivium, and it is their mine that has weakened the crater wall and is potentially threatening all the communities around with a possible catastrophic flood. Sulu meets up with Chekov, and they try to recover the shuttle, but find that it has been removed from the lake and loaded with the mined olivium. In a deal for the return of Uhura, Chekov agrees to pilot the shuttle for the Peacemakers, but he then refuses to fly them into orbit. Serafini (who had earlier killed the other Peacemakers on the shuttle) and Bartels get taken into custody, and Chekov gets injured. The wall of the crater collapses and the flood is heading for the town of No Escape as Sulu and Uhura vainly try to evacuate as many as possible. Thee crashes the olivium-loaded shuttle (after ejecting herself) into the ground ahead of the flood and creates another crater that entraps the flood. The Enterprise returns after the action has taken place, but in time to see, and destroy, a lone Kauld ship apparently making a suicide attack on the planet.