Nanclus was the Romulan ambassador to the Federation in 2293. In that year, he was involved in a conspiracy to sabotage peace talks between the Federation and the Klingon Empire. While in a meeting with the Federation President after the arrest of James Kirk and Leonard McCoy, Nanclus lent his support to "Operation Retrieve," the proposal to infiltrate Klingon space and rescue the hostages, put forth by Nanclus' fellow conspirator, Colonel West. Later, Nanclus attended the Khitomer Conference. After the crew of the USS Enterprise-A learned of his involvement in the conspiracy, and successfully prevented the assassination of the Federation President at the conference, he was detained by Starfleet. (Star Trek VI: The Undiscovered Country)