A convicted murderer volunteers for an exchange program between Earth and Chromo.
"In dreams, some of us trope the stars":
- Blob Monster: The Chromoite combines a gelatinous upper half with a humanoid body structure.
- Colorblind Casting: Diana Sands as Dr. Julia Harrison. A rare example of a black woman as a skilled professional (a doctor) in early-1960s US television. Her race is never even brought up in any way throughout the episode.
- The Grotesque: The faceless Chromoite, which vaguely resembles a humanoid jellyfish with crab-like claws, is one of the weirdest and scariest aliens created for the series.
- Poor Communication Kills: If the Chromoites had just asked for help with their famine instead of resorting to an elaborate conspiracy, they could have spared everyone a lot of trouble. Lampshaded in the episode's last line: when the aliens finally explain their true intentions, Kellander simply replies, "You should have asked".
- Sympathetic Murderer: Why is Chino in prison? Because when his sister became a junkie, he vengefully, impulsively killed The Aggressive Drug Dealer who got her hooked.
- Teleportation: The Chromoites have invented a "Teleportation Agency" that they use to send one of their people to Earth — and vice versa.
- Well-Intentioned Extremist: The Chromoite becomes a spy, a thief and a murderer in a misguided attempt to save his starving people.
- What Happened to the Mouse?: During the climactic struggle, an unconscious (or dead) human security guard is accidentally teleported to Chromo. We never learn what happens to him after that, and the characters don't even seem to notice he's missing.