As Victor and the colonists prepare to depart, they spot Jupiter 2 on the radar. Victor tries to raise them on the radio but gets no response, and Jupiter 2 flies over the desert.
In Jupiter 2, Will tries to spot the location on the ring where the lighting from the storm will help. They locate the lightning pillars on ring and land nearby. Will and Ben prepare to carry Scarecrow out, but the lightning storm arrives earlier than anticipated. Ben figures Will will be safe from the lightning in Jupiter 2, and tells the boy to stay there and when he gets to Alpha Centauri, tell his family that he tried to fix his mistakes before it was too late. He locks Will in the cockpit so Will can't chase after him, and then leaves with Scarecrow.
Ben reaches the spot where he has to place Scarecrow, and Scarecrow crawls the rest of the way. Will calls Ben over his comm and says that there must be another way, and Ben thanks Will for reminding him who he used to be. Ben then tells Scarecrow that the next time they meet, they should do things differently from the start. The lightning slams down, and the impact knocks Will back. When Will wakes up, he looks out and sees dozens of robot facelights. Going to the radio, Will sends out a mayday.
The Jupiters dock with the Resolute, and a tech finds Judy and Penny. He tells them that he needs to search their cart, and Penny breaks into tears and says that they're restocking their new Jupiter belonging to their legal guardians, the Osovedos. The tech offers his condolences on the deaths of John and Maureen, and lets Judy and Penny go on without searching their cart, and Penny stops the fake tears.
The sisters take the cart to the subsystem hatch and give food equipment to John and Maureen, hiding inside. They tell their parents that they haven't heard anything from Will, and John tells them to go before someone sees them. Don is hiding with them and starts cutting through the wall as Maureen calculates that the last Jupiters are arriving. The mechanic warns that he's trying to break into a place that was built to never be broken into, and wonders what happens when they get to the Robot. John says that they'll make sure the Robot's still on their side and knows a way to get to his colony.
On the bridge above, Hastings tells Kamal that they've picked up a signal from a Jupiter on Alpha Centauri, and the Robot will take the Resolute there. A tech reports that two ships are incoming and one of them is unknown while the other is a Jupiter. Victor reports that the alien robots are pursuing them and all the surviving colonists are on his Jupiter. The ships will reach the Resolute in ten minutes and twenty-eight minutes, respectively.
Will calls Maureen and says that he's with Victor on Jupiter 2 and the alien robots are coming,
Hastings goes to the Robot and warns Smith that he's going to open the Rift. He tells Smith that he's not going to sacrifice the other colonists to wait for Will.
The alien engines power up, and Maureen and John hear it. They realize Hastings is trying to leave, and Don warns that he can't burn through the ceiling time. John figures they can go in through the main door.
Hastings activates the Robot and tells it to take them to Alpha Centauri. He hesitates and mutters Will's name, and Hastings is surprised the Robot can still remember Will. John comes in, knocks out the guard, then encounters more guards and attacks them.
Hastings orders the Robot to take them to Alpha Centauri, and Smith worries that Hastings is breaking the Robot. Meanwhile, John knocks out all of the guards except one. Don arrives and knocks the guards out from behind, and Maureen comes in behind him and enters the engine room. She shocks Hastings with an electro-prod, then she and John free the Robot while Penny and Judy arrive. The Robot reactivates and they realize it's okay. Jupiter 2 docks with the Resolute, and Penny tells the Robot that Weill is there. Smith tells Maureen that she tried to stop Hastings, and Maureen isn't impressed. John tries to help the Robot up and asks for some help.
The damaged Jupiter 2 docks with the Resolute and the colonists are reunited with their families aboard the mothership. The Robinsons are reunited, and Will tells them what happened to Ben and how an army of the alien robots are on their way. John brings the Robot in, and Will runs to hug it and say that they got Scarecrow to the ring in time. Victor tells the Robinsons that they need to get away as fast as possible, and figures that the robots want the engine. Maureen asks the Robot to use the engine to take them to Alpha Centauri, and it says "danger". They realize the robots could follow them through the Rift and attack the Alpha Centauri colony, and they can't let the robots get there. Maureen says that they’ll stop the robots by letting them board the Resolute.
Techs set up the EMG devices in a cargo hold, and Will and the Robot bring in the engine. The alien ship is ten minutes away, and Will worries that they're killing a hundred Scarecrows after Ben died trying to save one. He worries they're not doing the right thing, and Maureen insists they have to protect themselves.
The alien ship continues approaching and Penny goes to monitor the robots from the surveillance room. She goes there with Will and the Robot, and John goes with Judy and the engine to buy them some time. They go to the Hall of Heroes and John warns that any metal caught in the EMF field will be crushed. Judy looks at the plaque for her father Grant. John assures her that Grant would be proud of her.
The robots board the Resolute and jam the surveillance cameras. Penny mutters that she has one job. Meanwhile, John and Judy carry the engine off and the robots follow, while Maureen continues powering up the field. When they reach a bulkhead door, John closes it and the robots start smashing through.
Will and Penny track the path of doors the robots are destroying to track them, and Penny warns Maureen that the robots are heading her way. The field is only at 80% power, and Maureen tells Don that someone will have to be at the door to make sure all of the robots are in the cargo hold. Don reluctantly volunteers and everyone else gets out.
John and Judy run in, and the robots follow them. They get to the other end where Maureen is waiting, and Don signals that all of the robots are in. Maureen activates the field and the robots are frozen just as they reach Maureen. John gets Maureen out, and Maureen says that they only got to 83% power. She figures that they can rewrite the room and increase the power to destroy them for good, and it will take the rest of the day.
Maureen goes to the bridge to redirect the power distribution, and Don accesses the grids in the room. The crew pick up hundreds of unidentified ships intercepting them, coming from the other four planets in the system. The ships will arrive in two hours
The Robinsons meet on Jupiter 2 and Maureen warns that they can't blast off the part of the Resolute with the robots without destroying the entire ship. They're out of EMF generators, but Will figures they can use the Amber Planet's ionosphere to magnetize the Resolute hull. Judy calculates that they can get 97 people into a Jupiter along with the alien engine, and notes that there are 97 children aboard the Resolute. Maureen refuses to discuss it, but Judy tells Maureen that Hastings told them what Maureen traded to get Will approved. She admits that she was disappointed in Maureen for the first time, but now she understands that sometimes an imperfect solution is all they have. Maureen insists that she did it so they could be together, and Judy tells her that she did what was best for her children. John agrees with Judy, and Judy says that she won't be going because she's 19. Penny insists that they're not a math problem, and Will points out that Judy has always said that Robinsons stick together.
John has Will confirm that the Robot can attach the engine to a Jupiter. Will finally confirms it won't be a problem, and John says that they'll tell the parents and each family will have to decide for themselves. Maureen talks to John privately, and Will and Penny refuse to leave without the rest of their family.
Maureen hugs John, breaks into tears, and says that she can't.
In the cargo hold, the robots slowly start moving.
The Robot places the engine in a Jupiter and activates it. Smith triggers a false carbon dioxide warning to get the workers to evacuate, goes to the cockpit, and when the Robot joins her, she says that it's just the two of them. The Robot refuses to go, but Smith insists that they've left her no choice because they didn't choose her for the evacuation. Smith wonders why she shouldn't launch, and the Robot stares at her.
A minute later, Smith walks out of the Jupiter and tells the mechanics that the CO2 levels are fine. The children start boarding, and one girl drops a ball. Smith picks it up, but the girl has moved on and Smith can't return it to her.
Don finds the Robinsons and says that he'll see them around. As he walks away, Penny runs over and hugs him, crying. John brings Penny back to the others, and says that he loves them. Maureen gives Penny a copy of her book Lost in Space with one page saying "Fill these" remaining empty pages. Will tells his parents that he always tries to be helpful but it's hard at the moment, and Maureen says that's what she loves about him.
Judy tells John that she's not going because she's not a kid anymore. John says that he only trusts her or Maureen to take care of his children, and he'll only get through it if he knows Judy is there. All of the parents have agreed that Judy should captain the ship to the colony, and it's time for her to be a captain. As Judy goes to the Jupiter, she wonders if she's supposed to make a speech, and John tells her that she'll figure it out.
Don and the mechanics join John and Maureen, and John says that they have a half-hour before the other ships arrive. They're going to board Jupiter 2, stock it with whatever they can carry, and scatter with the other transports. Maureen sees Smith and hangs back, and Smith says that she has nowhere to go. The Robot marches past, and Maureen and Smith follow him.
The Robot enters the cargo bay and says "Danger" to Maureen. She realizes that the general robot is reaching for the power cable to the EMG generators, but is moving so slowly they didn't notice. Maureen shits the power cable out of the general's claw, but they see another robot reaching for the main power cable. A third robot opens the airlock, revealing the launching bay outside. The Robot can't go in because it's made out of metal, and Smith puts on a suit. She seals Maureen in the hub closet, grabs the ball, and tells Maureen over the intercom that all she has to do is move a wire. Maureen warns that the EMF field will crush metal like Smith's suit, but Smith says that she'll go fast and enters the cargo bay. As she moves, Smith tells Maureen that she's making the sacrifice because the Robot said "family", and the Robinsons are the only family Smith still has. She moves the wire and the Robinson kids will be safe, and it will be worth it.
Smith makes her way to the main power cable, fighting against the EMF field. She moves the cable but sees other robots reaching for other cables. Maureen runs out, still calling to Smith on the comm, and looks outside to see Smith's suit drifting out the airlock door. Shocked, Maureen admits that Smith surprised her again and radios John to tell him that they have to launch immediately because the robots will break out in minutes.
John tells Judy to launch because the robots are coming for her Jupiter. Judy tells Penny and Will and they begin the pre-launch. Meanwhile, a robot in the cargo bay severs one of the cables and all of the robots move at regular speed, heading for the childrens' Jupiter.
In the Jupiter engine room, the Robot realizes that the other robots are on the move. It walks out and Will tells it they need it to stay with them so it can pilot them to Alpha Centauri. The boy asks the Robot to look out for the other children the way he looks out for Will, and says that he has to do it before going out. Penny sees Will going, and he goes out to confront the approaching robots. Will tries to control them and the general steps forward. The general says Will's name, and Will says that they don’t have to fight. The general looks at its soldiers and then prepares to attack Will... and Scarecrow leaps down and knocks the general to the floor.
Penny gets Will back aboard the Jupiter as the general recovers. Scarecrow blasts it and fights the other robots, As they strap in, Will blames himself for thinking he could change the robots. Penny points out that he was able to change two robots.
The general sees the Jupiter leaving and slams Scarecrow through the window. It pulls itself back in and fights, while the other robots are sucked out into space. The general finally smashes Scarecrow down and prepares to open fire on the Jupiter, but Scarecrow recovers and knocks the general away from the window. A stray shot hits the Jupiter, knocking out the accelerator. Judy radios John, saying that they can't open the Rift too close to the Resolute and they can't accelerate away. Maureen tells Judy that they'll make sure she and the others are okay. Don tells them that he's in for whatever they're going to do, but John tells him to take care of the others. As soon as John and Maureen clear the airlock, Don launches Jupiter 2 and departs with the other Jupiters.
John and Maureen go to the bridge and Maureen lowers the bulkhead doors to slow down the swarming robots. The Resolute doesn't have a self-destruct, and they don't have time to crash the ship into the planet. and Maureen says that they're going to crash the Resolute into the deck section they blasted clear to stop the rust. The computer overrides their attempts to collide, and Maureen radios Hastings to ask him to get the access codes so she can destroy the robots and protect the children. Hastings sends the access codes and Maureen enters them. Maureen tells Judy that they're good to go, and John leads Maureen off once the course is laid in.
Once the Jupiter clears the Resolute, Judy tells the Robot to take them to Alpha Centauri, and it opens the Rift.
John and Maureen head for the pod bay but realize they won't make it in time. As they kiss, Don pulls up outside the nearby window and asks if they want to get rescued.
The debris slams into the Resolute, smashing it apart. The alien ship pulls free at the last minute and flies clear, Jupiter 2 paralleling it. The alien ship flies into a strut and is destroyed, and Jupiter 2 flies clear. John and Maureen are with Don, and they watch as the childrens' Jupiter enters the Rift. John wonders how they're going to find them, and Maureen figures they'll figure something out.
The Jupiter arrives near Alpha Centauri, and Judy tells the children to hold each others' hands. Penny and Vijay hug, and everyone grabs somebody else's hands. Judy says that Scarecrow saved them and none of them are alone now even if they're strangers.
The Robot releases the engine and looks down at a container holding Smith's headband and the ball she found.
The Robinsons and Vijay look out the port at the nearby planet, and the Robot joins them. Will tells it that Scarecrow saved them, and wonders if the Robot knows what hope is. It says that it does, and Penny realizes that Alpha Centauri looks different than what they saw before. There's only one sun instead of three, and as they see the planet they realize that it's been shattered. Judy confirms that they followed a human-made radar signature, but it's not the colony. They see a ship ahead and realize that it's the Fortuna... which was lost 20 years ago in space with Judy's father Grant commanding.
Written by Gadfly on Jan 5, 2020