Previously, John Robinson took a spacewalk to fix the ships NGS Scanner. His tow line broke and Maureen suited up and shot him a line using a rocket gun, it missed.
Now, she pulls the line back resets the gun and shoots again, this time John catches the line and is pulled towards the ship. Meanwhile, the ship detects a comet heading towards the ship, Don tells John and Maureen to come back into the ship and repair the scanner later. John decides to fix the Scanner now. Smith reprograms the Robot to respond to his voice commands only. John and Maureen finish the repairs and see the comet heading in their direction. They try to enter the ship and the door is jammed, the heat from the comet has expanded the metal. Don suits up, gets in the airlock and tries to the door manually from the inside. Will suggests using a fire extinguisher to cool down the metal, Don agrees. Smith gets a large extinguisher for the lower level. John and Maureen collapse.
At Alpha Control, it is October 21, 1997. All efforts to re-establish communications to the Jupiter 2 have been unsuccessful. They believe that sabotage is the reason for the problems. The fire extinguisher works and the door opens, Don pulls John and Maureen into the ship. Don pilots the ship away from the comet.
Smith tests the Robot with a series of commands to see how it reacts. John fills out his daily log. Don and Judy talk about the ships position and the stars. John checks in on Penny as she listens to Shakespeare. He checks in on Will, who is trying to calculate their position. John checks in on Smith and finds him working on components from the Robot. He takes the components from Smith and says he considers him a stowaway.
Don picks up a signal, a ship is comes into view. John wants a closer look and tells Don to head towards the ship. It turns towards the Jupiter 2. It opens up and starts to pull the Jupiter 2 in. Once inside, the ship closes and the Jupiter 2 lands inside. Smith thinks the ship is from Earth.
John, Don and Smith go out to investigate. While searching the alien ship they find a control panel. Smith goes off by his self to try and locate anyone onboard as John and Don try to figure out the control panel. Will sneaks out of the Jupiter 2 and explores the ship. John figures out how to get star maps up for viewing. Will comes across an alien being and tries to communicate, Smith shows up and pulls his gun, will stops him. Smith tries to communicate and gets aggravated when the alien does not respond. He shoots the alien. The alien moves towards Will and Smith.
John and Don hear Wills cry for help and attempt to locate him. They find Smith and Will and head back to the ship. John holds off the alien rocklike creatures while Don gets the Jupiter 2 ready for liftoff. Don puts up a force field. John comes onboard and the Jupiter 2 lifts off. The spaceships doors open and the Jupiter 2 exits.
Later that evening John fills out his daily log explaining that he was able to find a planet using the alien's star charts. They decide to land on the planet for repairs.