A Cardassian border world where a rumored biological weapons facility proved to be a trap to capture Captain Picard.
Celtris III is a Cardassian world on which Starfleet believed a secret biological weapons laboratory had been built. Its caves made a covert approach possible.
In Chain of Command, Picard, Worf and Dr. Crusher are sent to infiltrate and destroy the facility. They find no weapons, and the Cardassians capture Picard, revealing that the whole operation was bait. Worf and Crusher escape, while Picard is taken to Gul Madred for interrogation.