On Novus, the alternate Colonel Young is dying of old age while Chloe watches over him. He calls for his son, Steven, who arrives and assures him that Sara will be there shortly. Young says that he’s sorry.
Scott lands the shuttle on Novus near a city covered in ash from the volcanic activity. After performing a recon, they report to the ship that the city is abandoned, and Yaozu has directed to a giant fallout shelter. They need Young to open fire on the shelter’s doors with Destiny
’s main weapon at 60%. They successfully blast open the doors and go inside, and Yaozu escorts them to an elevator that leads into the complex. At the bottom they find a vast uninhabited archive filled with records of the planet’s entire history.
Yaozu shows the crew the footage of their alternate selves arriving on the planet two thousand years ago. Eli establishes communication and Scott reports that they haven’t found anyone, but the complex has plenty of power. Rush focuses on salvage, and Scott says they’ve found survival rations. Young authorizes shuttles to bring up the supplies and sends Rush to the planet.
Two thousand years ago, their planet’s atmosphere is too thin and Eli sends kinos through to the four planets within range of their Stargate to find one with a breathable atmosphere.
Rush arrives on the planet with the others and goes to join Scott and Greer on their search for supplies.
Scott and Greer find an inhabitable planet and Young starts sending people through.
Eli suggests that they stream the data from the archives and send it to Destiny
. Volker points out that Yaozo doesn’t like Brody tampering with the computers since he’s the founder of the enemy nation of Futura. Park watches footage of the original settlers arguing about whether Rush will come rescue them. In the past, Young says that there’s no point in waiting and organizes teams to start building a camp.
Rush finds Greer, who has located beef jerky. While Eli prepares to upload the information to Destiny
since they don’t have enough time to read it all. Scott goes to see Chloe, who is looking through the thousands of books, many of them written by Eli. She has found her diary, which relates what happened in the early days.
Brody argues with Eli about where to settle, insisting they should stay where they are. Losing his temper, Brody blames Eli and his calculations, but Young interrupts to tell them to get back to work.
Before Chloe can read further, a tremor shakes the complex, cracking open one wall. Scott calls for additional teams to accelerate the process.
Camille and Johansen are working on a garden when Volker collapses. His kidneys fail and Johansen is unable to heal him without the Ancients’ medical equipment. Shortly thereafter they conduct their first funeral.
Volker watches the footage of his counterpart’s death. Park arrives to report that the shuttle is ready to take Volker to Destiny
to supervise the uplink from that end. Meanwhile, Johansen tends to Yaozu, who received minor cuts during the tremor.
Johansen stitches up Young after he suffers an injury during construction. Varro comes by and Johansen tells him to take it easy. As Young starts to leave, he wavers from the stress and Johansen tells him that no one blames him, and they should make the most of their new lives. They kiss as Varro watches.
Eli checks the records and finds out that the planet’s Stargate was buried in lava decades ago. The two nations pooled their resources and built generational evacuation ships to travel to one of the planets they had explored.
Scott talks to Vanessa James, who is proud of the next step that he’s taking and says that he should be proud. She assures him that she’ll be there for the first wedding on Novus. As the ceremony proceeds, Varro and Vanessa exchange looks. Eli records a log later complaining about how everyone is getting together except for him and Brody.
As Volker begins the uplink, Park locates records of a partially-completed evacuation ship that is still on the planet at a factory. As Eli watches footage of a pregnant Chloe saying that the other Eli will be a great uncle, Park taps into the geothermal records and realizes that a black hole has entered the system and the tidal forces are ripping the planets apart. There are fissures beneath the city and lava is coming up, and Eli warns that they need 37 hours to upload all the Teneran archives.
Johansen and Young have their first son. Chloe gives birth to a child. Park ends up with Greer and has a son who they name Dale. Eli is still depressed that he’s alone until he links up with Corporal Barnes, and she soon has a son with him.
Eli and Chloe watch the footage, and Chloe suggests he might pursue a relationship with his Corporal Barnes.
Rush finds slabs of a grey foam-like substance among the supplies. Another tremor sweeps through the complex as the fissure beneath the city grows ever wider.
Camille talks about her date with one of the colony’s women, but says that she isn’t interested because she has already found her soul mate and isn’t looking for another. As Johansen stops her son Steven from eating the corn, she feels a pain in her wrist.
Young tells Scott to check out the ship, and Rush asks him to take him back to Destiny
after they visit the factory.
Johansen’s pains grow increasingly stronger and she records a log describing how she is suffering from ALS: Lou Gehrig’s disease.
Johansen sees the video and Varro comes to reassure her. However, she says that it’s a genetic disease, not something she can contract, and there’s no cure.
Scott, Rush, and the Tenerans fly toward the factory but discover that it has been covered in lava.
Young comes to see Johansen and tells her that Volker is checking the Ancient database for a cure. She explains presented five years after they arrived on Novus, and she died a few years after that. Scott calls in to report that the ship has been destroyed. Rush advises them to leave the planet and Young agrees, ordering an evacuation. When Scott points out that they don’t have enough supplies to take the Tenerans to their new homeworld, Rush says not to worry. Johansen bursts into tears and Young comforts her.
Johansen gets steadily worse and Young does what he can to take care of her. She finally dies, leaving a husband and two children behind.
With time running out, Eli warns that they have only transferred a third of the information. Another tremor shakes the complex, and Young tells everyone to head to the surface. However, Yaozu tells Johansen that they developed a cure for ALS two hundred years ago, and the information is stored in the archives.
Volker calls Rush and asks for help finding the ALS cure, but he says he has something more important to do.
The original settlers grow steadily older have grandchildren. Camille, alone, drafts a constitution. Eli teaches the children. Brody complains about the children dancing on his lawn.
Eli warns that he had to compress the data into one file, and he can’t confirm that the ALS cure is in that file, or the 33% they’ve sent to Destiny
. Varro says that they should wait as long as possible, but another tremor shakes the complex, trapping Young, Johansen, Varro, and Eli.
Young is elected leader of the settlement, but some of the settlers prepare to leave for another planet.
Young contacts Scott and tells him to stand by, and then he and the others start climbing up the weakened ladder. Eli goes first and makes it to the top. As the others climb, Johansen’s rung breaks and she falls, but Varro manages to catch her. He swings her to a ledge but the effort causes him to fall down the shaft. Scott and Greer lower a rope and pull up Johansen, while Young goes down after Varro. The others pull them both up and they leave the planet just as the lava engulfs the complex.
As Young lies dying, he apologies to Chloe for never getting them home. As his children gather around their father, Chloe tells Young that they are home.
The foam that Rush found is a high-quality CO2 scrubber and he uses it to replace the lime filters. Volker asks Rush if it bothers him that everyone got by fine without him and Rush has no answer.
Johansen manages to stabilize Varro but warns that all they can do is wait. Eli tells Johansen that the ALS cure wasn’t among the data that they transferred, and there’s nothing in the Ancient databases. She suggests that they talk to the other Tenerans when they drop off their Tenerans, but Eli points out that those ships won’t arrive for 200 years. He promises Johansen that they’ll find a cure for her.
Eli’s grandson Matthew dedicates the settlement’s new school to Eli, and has the last original Destiny survivor address the crowd. Camille steps forward and tells them that at first they believed they had failed in the mission, but learned that the mission was the journey itself.