The episode begins with an unidentified object following the Christa. This goes unnoticed by the crew who are at the command post, preparing something to drive Ms. Davenport crazy. Ms. Davenport enters and asks Harlan to promise her that their lives are not in danger. He answers "Oh, don't worry. Everybody inside the ship is safe." Ms. Davenport then says "Well, that's a re - who's not inside the ship?" Then the kids pull up an image of Commander Goddard on the screen floating through space outside the Christa. They explain that while he was fixing something outside the ship Catalina and Radu had accidentally flushed him out. Ms. Davenport tells them to do something and they tell her they have a tractor beam locked on him but they don't know how to use it and if they are not careful they might blow him up. She tells them that they have to get him back on the ship. Harlan says ok, moves a lever and the Commander explodes. At the exact moment Goddard comes through the jump tubes asking what all the commotion is about; and Ms. Davenport screams and faints. Harlan explains that they had just blown up a computer simulation of him to play a prank on Ms. Davenport. The Commander tells them they need to grow up and that the Christa is not a toy. Then he banishes them to their quarters until further notice.
Just after the kids leave the mysterious object that had been floating alongside the Christa materializes in the command post. Ms. Davenport thinks that it is another prank but Goddard tells her that pranks don't teleport. He says it looks like some kind of space probe and as he reaches out to touch it a bolt of electricity comes from it hitting both the Commander and Ms. Davenport. Gas begins to escape from the bottom of the probe causing them both to fall to the ground in coughing fits, but on the way down Goddard manages to hit the alarm. The probe shakes back and forth and what sounds like mechanical laughter comes from it.
Having heard the alarm Radu, Harlan and Catalina return to the command post and see the space probe along with two children who don't look like aliens. The children are a young Seth Goddard and T.J. Davenport. In the lounge the crew explains to the children how they came to be on board the Christa and how they have a long journey home. When Goddard asks about the grown-ups Radu tries to explain that they are the grown-ups but the young Ms. Davenport doesn't believe him. Radu yells at Harlan saying that if he hadn't turned the computer off to play his prank then the alien probe would not have been able to get on the ship. Now convinced that they were the adults young Goddard asks what they are doing to contain the probe. Harlan, Radu and Catalina go back to the command post and set up a power fence that supposedly nothing can get through.
Back in the lounge Rosie is unable to find anything in the medical files that would change the Commander and Ms. Davenport back to there normal selves; she and Catalina are discussing what they should do when Harlan interrupts. He talks about how they don't like Davenport ordering them around and how the Commander is not a fun guy and how he likes them better as kids, now they are equal and they don't have to do anything. Then the entire crew heads to the gallery where a massive food fight ensues. Watching the food fight on screen the alien probe, in which nine heads can now be seen through the side say that "frivolity is not productive" and needs to be punished severely. This is repeated by Thelma. The probe fries the power fence using an electric charge; and takes control of the command post.
In the galley things have calmed down and Radu and Catalina start arguing with Harlan saying that things were out of control. When Radu mentions that they haven't even run a check on the ships diagnostics Thelma informs them that their course has been changed and they are now heading in the opposite direction toward a planet as ordered. Radu tells them that the course change was not an accident and that something had taken over the ship. They head to the command post where the alien probe identifies itself as Neinstein, nine scientists who had been on a mission of great importance and whose ship had crashed rendering their physical bodies useless and forcing them to transfer their minds to the space probe. They turned the Commander and Ms. Davenport into children so that they could be of use on the 70 year journey back to their home planet and print out a list of new rules for the kids to follow. Catalina tries to blast them with a sonic wave but is zapped before she has the chance. The children attend lessons taught by Neinstein and if they do not follow the rules they will be zapped. Thelma as well has been taken over and is under the control on Neinstein.
In the middle of the night Harlan sneaks into the girls bunk room and wakes up Catalina, where the whole crew is meeting to try and come up with something to do to get rid of Neinstein. Neinstein is monitoring the jump tubes but the crew decides that if they crawl through the jump tubes while they are turned off they can surprise him; then by running a cable from the engines and making a direct connection to Neinstein they could hit it with a proto-mix overload and get rid of it. They sneak through the ship hiding from Thelma along the way. Goddard doesn't like the plan and wants to use himself as bait by going out the airlock. Harlan thinks that they should stick to the plan and even if the blast doesn't destroy Neinstein the shock should distract him long enough for Davenport to regain control of the computer. Goddard goes off on his own to implement his plan. Meanwhile while Rosie, Bova and Davenport distract Neinstein Harlan and Radu attempt to connect the cable, but it is too short. On the screen Goddard is seen floating through space. Bova grabs the end of the cord but even then it is still too short. Just then the Goddard on screen explodes and young Goddard comes down the jump tubes with an energy bar that he gives to Bova and now reaches Neinstein. At first it doesn't seem to be working but Catalina engages the hyper drive and Davenport is able to regain control of the ships computers. The nine personalities have now been combined into one personality; grateful for the clarity of only one personality Neinstein makes improvements to the ship and agrees to leave. Ms. Davenport and Commander Goddard are changed back to their normal selves and only have a vague memory of what had happened.