What Ships Are For

Admiral McGuinness of Starfleet Medical sends the Enterprise to Hyalinus, a reclusive asteroid world whose people are dying from an illness caused by their sun's radiation, which has also robbed them of colour vision. Kirk, Spock and McCoy meet council leader Galisti and his wife Thaius, who distrust outsiders; one councillor, Tomiat, even threatens to shoot himself in protest until Spock nerve-pinches him. McCoy brings a young patient, Sekara, aboard, where she sees colour for the first time and grows close to Kirk. When shuttles carrying Ambician travellers approach, the Hyalini open fire on the people they call savage invaders, and Kirk destroys their orbital weapon. Spock's scans then reveal the truth: Ambician refugees have lived unnoticed among the Hyalini for generations, indistinguishable in a world without colour, and Sekara is one of them. Curing the disease will expose everyone. Galisti argues that admitting a few invites all, while Dr McKennah reminds Kirk that turning away the desperate betrays his own values. Kirk talks Sekara out of sabotaging the probe that will deliver the cure, then urges the council to stop hiding: a ship is safe in harbour, but that is not what ships are for. As colour returns, Galisti discovers that Thaius is Ambician too, and the two peoples begin to see themselves as one.