Keyla Terrana was a mysterious woman whom Jonathan Archer met while vacationing on Risa in 2152. Although she appeared as a member of a previously unknown species, she was in fact a Tandaran in disguise.
On Risa, Keyla was staying in a villa across from a villa which Archer was occupying. She had with her a dog named Rhylo. When Rhylo somehow appeared on the deck of Archer's villa and began a growling match with Archer's dog, Porthos, Keyla arrived to retrieve Rhylo. Keyla became acquainted with Archer and accepted his offer to join him for dinner the following night.
Although she seemed to be making romantic overtures toward Archer, Keyla remained secretive and avoided answering Archer's questions regarding the name and location of her planet. She eventually told Archer that her family, including her husband, had been killed by the Suliban Cabal. When Archer admitted he had had encounters with the Cabal, Keyla suddenly deluged him with questions regarding those encounters, asking where they lived and wondering what they were planning next.
Surprised by Keyla's tenacity and noting that she was asking questions similar to ones he had been asked by Tandaran Colonel Grat, Archer took a bioscan of Keyla, revealing her to be a disguised Tandaran. Archer confronted Keyla with the truth, asking her if she had been sent by Grat and accusing her of creating "fictitious tragedies" to gain his sympathy. Keyla appeared to have no knowledge of Grat and told Archer he was wrong about her, insinuating that her "tragedies" were very real. She attempted to leave, and when Archer attempted to hold her back to get more information, Keyla rendered him unconscious by pricking him with some type of anesthetic. She then left, proclaiming that she could not have Archer interfering with her plans. (ENT: "Two Days and Two Nights")