After Commander Koening's Eagle crashes on the planet Zenno, his soul is captured and scrutinized by a resident alien, due to the fact that we humans appear to be their missing link.
OH THE NOSTALGIA! In French, this was "Le maillon" (or, "The Link"). I don't remember it.
REVIEW: Taken literally, Missing Link smacks of a bad Season 3 Star Trek episode. Commander Koenig is kidnapped by aliens, put in a vaguely surreal environment, and experimented on/studied, only getting released after falling in love with the scientist's daughter and teaching her human values. Ugh. While there are some good moments, including some effective nightmare imagery like people with their brain pans open, it all comes down to a tepid and unjustified romance between our hero and the guest alien. Nothing really justifies it, or Koenig's decision to leave Alpha and its responsibilities, unless he's really being telepathically manipulated. Surely, the reverse cannot be true, since these super-telepaths would know if he were deceiving them. As for the idea that humanity is the "missing link" in these people's evolution, people who live 5 million light-years from Earth in another galaxy, it's best left unexamined. In fact, it's not even clear if we are LIKE their missing link, or actually are, somehow.
What saves the episode is that it's all happening in Koenig's mind. After an attempt to explore a planet with vestiges of an ancient civilization, his Eagle loses control and crashes on the Moon surface. If he's really been taken by the Zennons, they only have his mind, and are willing to let his body die in the real world. There are various clues that point to this being a hallucination: His name misspelled on his POV of his life monitor, Sandra only appearing after he might have heard her try to save his life, and the aliens calling his body an "image" (so a projection for the Alphans' benefit?), but being flesh and blood when he wakes up. Scenes between Zennons only kind of defeat the purpose, even though we can say Koenig could be having a third-person-omniscient dream. And Sandra seems to react to his awakening as to suggest she remembers being in the shared reality, but since she was told she wouldn't remember any of it, that's ambiguous at best. If it's all a dream, what does the dream mean? A longing for a place to call home (note the absurd ties to Earth), romantic feelings for an emotionally-repressed woman (also note the look between him and Helena when he wakes up), and the trauma accompanying his head injury (the monsters he sees speak to this). Dream Victor calling the Moon their tomb is out-of-character for him, but is perhaps indicative of Koenig's own doubts and fears. This is a much stronger take on this episode than having it happen literally.
Regardless of whether or not Missing Link is an imaginary story, the drama Moonbase-side is good. Helena struggles to save Koenig's life, but must come to the only possible conclusion that he's beyond help. Though no one wants to accept her prognosis, she still pulls the plug on his life support, even if it does cause her great pain. Everyone on Alpha is more emotional than she is - Alan Carter even starting a fight in sickbay, his unflinching loyalty unable to let him even accept a temporary leader - so they're unlikely to realize her quiet suffering. The portrait of Alpha as a dysfunctional place without Koenig's direction is a bit extreme - Kano is doomed to be the jerk in every episode, it seems - but keeps the episode tense when we're not dealing with the A-plot.
HEY, ISN'T THAT... Peter Cushing is the scientist Rann; he's been Van Helsing, Doctor Who and Grand Moff Tarkin, and I guess he's also been a gold alien in a colorful baker's hat. Joanna Dunham is his daughter Vana; she's best known as Mary Magdalene in The Greatest Story Ever Told.
REWATCHABILITY: Medium-Low - I like it better if it's all a dream (Medium), but that doesn't appear to be the intention. A dull romance and no real explanations for what's going on.