A star system in Klingon territory whose sun leaves visitors unable to see colour, where Una, Uhura and M'Benga are stranded on occupied Mat'Aar XII.
The Mat'Aar system lies inside Klingon space. Radiation from its star leaves people there unable to perceive colour, and the Strange New Worlds fourth-season episode A Case of Chiaroscuro is accordingly presented in black and white. Its inhabited world, Mat'Aar XII, has a human-looking population living under Klingon occupation, governed by Kor.
The USS Enterprise is sent to recover a Federation probe that has shut down in the system. Una Chin-Riley, Uhura and M'Benga go in by shuttle and are forced to land when a D7 cruiser appears.
Una is mistaken for Nevette, a bar owner secretly tied to the resistance. She chooses to help the rebels, and an electromagnetic pulse device disables Klingon technology across the planet before it can be sealed off.