A people who believe they need a medicine from the neighbouring Brekkians to survive a plague, unaware that the plague ended long ago.
The Ornarans share a star system with the Brekkians. Generations ago a plague struck Ornara, and the Brekkians supplied a drug called felicium that relieved the symptoms. The plague has since ended, but the drug is a narcotic, and the Ornarans have become addicted to it while the Brekkians keep the truth hidden and grow wealthy by selling it.
In the episode Symbiosis, the Enterprise-D rescued both sides from a failing freighter and Dr. Beverly Crusher uncovered the deception. Captain Picard concluded that the Prime Directive forbade him to change the arrangement, but he refused to provide the replacement coils the Ornarans needed to keep their freighters running, leaving them to face withdrawal and discover the truth for themselves.