After months of searching, SG-1 has found a new home for the Enkarans: P5S-381. The lush,beautiful and uninhabited world has just the right conditions for the simple people -- a high enough ozone concentration to meet their physiological needs.
After two weeks of helping the small civilization relocate to this world, SG-1 joins them in a feast of celebration. But the party is cut short; a young man comes running from the west, reporting a terrible danger. An enormous alien ship (some two miles in diameter)is slowly moving across the planet's surface, destroying everything in its path with a 20-mile-long energy curtain.
The team studies the situation, and concludes that the vessel is terraforming the planet for a type of life unlike any they know -- sulfur-based life, rather than carbon-based. The terraformer will render this planet inhospitable to the Enkarans, and most certainly kill them if they are still there when it hits the village. And it is only a day away.
The Enkarans refuse to leave. They could not possibly evacuate the thousands of people they have, spread out over many villages, in time. And if they went to Earth, they could survive for only days without another high-ozone planet to live on. The only other suitable planet they know of is the original Enkaran homeworld, lost for centuries since the Enkaran's ancestors were kidnapped by the Goa'uld -- who came in ships, since the planet does not have a Stargate.
When General Hammond refuses to provide men and material for a military strike on the enormous ship, SG-1 has only one option: try and talk to them. They set up a transmitter,and soon the team is transported aboard the advanced vessel.
They are greeted by Lotan -- a bio-mechanical lifeform created by the ship in the image of the Enkarans, to best interact with them and explain the danger they are in. Lotan looks Enkaran, but is determined to do nothing outside of its programming: to serve the life on board this ship.
The ship, he explains, carries the last hope of an extinct species. The Gadmeer were a10,000-year-old, highly advanced and peace-loving people, overcome by a stronger military power. Rather than embrace extinction, the Gadmeer filled the ship with genetic samples of its race, and of plants and animals from their world. The ship's computers were filled with all the knowledge, art, music and philosophy of the Gadmeer.
The vessel was programmed to locate a suitable planet where the Gadmeer civilization could be reborn, far from their enemies. It selected this world, the new world of the Enkarans, and began terraforming it. Now that the process has started, it cannot be stopped. The ship does not contain enough materials to begin the transformation again on another planet.
SG-1 is faced with the extinction of the Enkarans, or the loss of an advanced civilization.It is a no-win situation. While Jack is bent on saving the Enkarans, Daniel wishes he would consider some means other than destroying an advanced civilization that is trying to fight off extinction.
Jack considers attacking the ship, and orders Major Carter to convert the naquadah reactor(brought to power the Enkaran city for the next year) into a naquadah bomb. He is hesitant to order her to do it, and she is hesitant to agree. But the device is rigged to detonate,and placed in a strategic spot to impact the ship when it passes overhead.
Meanwhile, Daniel has returned to the ship to try and give Jack another option. He convinces Lotan to see the world that he is destroying, and to meet the people he is going to kill. He tries to get Lotan to think outside of his programming. Lotan agrees to go, and the two explore the gardens of the world below. The terraforming process, however,continues to march slowly toward the village.
Lotan sees Daniel's attempt to elicit sympathy for the Enkarans. He does not want to see them destroyed, but is not programmed to consider alternate solutions to their problem. Here turns to the ship -- and Daniel goes with him -- and the terraforming continues.
Jack is hesitant to start the reactor's feedback loop, with Daniel now back on board the ship -- but he makes the difficult decision to activate it. The device is only minutes away from detonating.
Daniel continues to work on Lotan. How, he asks, can the peace-loving Gadmeer civilization be reborn through an act of mass murder? Lotan's true function, Jackson argues, is not simply to serve life on the ship -- but to serve the integrity of that life. Lotan is convinced, and stops the ship just shy of the village.
The naquadah bomb is detected, and Lotan transports it up to the ship. Daniel tells him that he has no way of deactivating it. With only seconds remaining, they fire the bomb into the sky. The ship escapes the enormous explosion.
There is silence as the two parties wonder what to do now. Daniel asks Lotan if, while examining millions of planets, the ship found any that would suit the Enkarans. For the Gadmeer, 2,634 specific parameters had to be met. One world was rejected based on only three: its core temperature was too warm, it was too large, and intelligent life was already present -- Enkaran life.
Daniel and Lotan return to the surface to offer a deal to the Enkarans. They will give up this world for the Gadmeer -- and in exchange, Lotan will take them to the Enkaran homeworld,the world of their ancestors. The Enkarans are overjoyed, and accept the offer.
After that, the ship will return and finish the terraforming process. But Lotan will not be reabsorbed into the ship's systems. He agrees to stay with the Enkarans, since he is, in fact, an Enkaran himself.