In this episode, Lt. Worf, the Klingon Chief of Security of the Federation Starfleet Starship USS Enterprise must work with his human adoptive brother Nikolai Rozhenko, a Federation anthropologist to save a small segment of natives from a primitive alien culture on a dying planet.

The Enterprise receives an emergency distress call from Rozhenko, currently posted to Boraal II, a class M planet in the process of suffering an atmospheric catastrophe.

The Federation observation post is found to be deserted, but force field shielding has been set up nearby which protects a series of caverns. Enterprise Captain Jean-Luc Picard decides to send an away team to investigate. Concerned for his brother, Worf volunteers, and Picard orders him to go alone and be surgically altered to pass as a Boraalan. Worf transports to the planet and discovers that his brother set up the shield to protect the local villagers.

Rozhenko meets with the ship’s senior officers and describes his plan to save one village of the doomed planet by setting up a concealed artificial biosphere. Picard replies that the Federation Prime Directive prohibits interference with the natural development of the Boraalan civilization; it is not for them to decide that one group shall survive while the rest of the planet perishes.

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