The Alphans enters a parallel universe and believe the "unknown force" took them back home. Commander Koenig finds that hard to believe and when they were ready to accept it another mystery arises and the existence of the Alphans and Moonbase itself is put on the line. Alphans had to deal with an earth that is not their home as they expected, with few human population. They do not welcome them either. Finally they have to make a tough decision if they want to survive. There is an amusing moment when a Main Mission operative (Paul) can be seen briefly using his commlock as a computer punching buttons frenetically, when I watched it the first time as a kid I found it unbelievably to use such a tiny device as a computer. Today is common to see people punching buttons frenetically in their smartphones. The episode arise again the concept of a God or Force that guide their destiny like in Black Sun and have good performances from the cast, specially Victor Bergman (Barry Morse). Great dialogue and good ending.