While out watering flowers, Penny encounters a man and his golden android. The man introduces himself as Sesmar and his android as Raddion, a project which has been his life’s work. Sesmar asks Penny many questions, especially about human feelings. Penny later tells her family about the strange encounter, but no one believes her. Her mother thinks she is suffering from heatstroke.
Later, Dr. Smith overloads the newly repaired air-conditioning and is ejected from the ship. That night, as Smith is sleeping outside, two small golden androids take him to Sesmar’s laboratory. After Sesmar analyzes Smith’s character and finds it extremely immoral, he decides to reduce him to his chemical components and put him back together as a better person. Smith counters that he would make a useful assistant, so Sesmar, agreeing, gives him a transpiration camera which he is to use to take pictures of the Robinsons’ feelings. Smith sneaks into the Jupiter 2 and photographs the other. When caught, he explains he was merely taking photos for sentimental reasons. He returns to Sesmar, who is very happy with the transpirations.
When the transpiration plates do not have the intended effect, Sesmar realizes that direct physical contact is necessary and invites the Robinsons to visit his laboratory. Everyone except Don shakes the android’s hand as it thanks them, and experiences a strange sensation as their feelings are transfered to the android.
The next day, Don and the Robot find the Robinson family acting listless and apathetic. Don returns to Sesmar’s laboratory to find proof that he is responsible and to resolve the situation. Meanwhile, Sesmar has found Raddion to have become too sentimental, and decides to add some of Don and Dr. Smith’s negative emotions to balance the Robinsons’ positive contribution. Before the process can be completed, Don and Dr. Smith trick the android into destroying Sesmar’s lab and Don destroys the transpiration plates before he and Dr. Smith escape. Sesmar realizes that his work with Raddion is far from complete and decides to return to his planet to continue his work on him.
- Just before the final fight scene in Sesmar's headquarters, Raddion's feet can be seen in the background while he is waiting for his cue to come on camera.
- Raddion is an anagram of Android.
- When Sesmar visits the Robinsons he offers them a "digitizer" as a gift, claiming it will increase the efficiency of the Robot. Presumably the Robot is analog.
- Sesmar comes to the Jupiter 2 to discuss his work with Raddion and to convince the Robinsons to come and visit his laboratory. The Robot is standing nearby and overhears the entire conversation, but it isn’t until absolutely everyone has already left the room does he wave his hooks in the air and give warning that “Bio-physical experiments are dangerous to humans!”
- When the project he has devoted his entire life to is destroyed, Sesmar isn’t all that upset. In fact, he seems completely nonchalant and just shrugs his shoulders, saying, “Back to the drawing board.”