Born in 2247, she was the daughter of Anton Karidian. She was a Shakespearean actress in the Karidian Company of Players. Anton took care so that his daughter never learned of his past identity. However not only did she do so, but she also became determined to silence all those who could connect Karidian to his past as Kodos by murdering them.
In 2266, the Karidian Company visited Planet Q to perform Macbeth. Attending the play was Thomas Leighton, one of nine eyewitnesses to an order of execution given by Kodos when he was governor of the Tarsus IV colony. A burned body was found by the relief forces, and Kodos was assumed to have died. Leighton believed otherwise, although he could not then convince James T. Kirk.
Leighton's beliefs turned out to be accurate: he was murdered as he walked home from town. His body was found by Kirk, who by that time was courting Lenore. Leighton's murder deepened Kirk's suspicions to the point that he contrived that the company would be forced to rely on his starship for transportation, so that he could widen his investigation.
Indeed, Lenore beamed on the USS Enterprise and requested that Kirk provide transport to Benecia. As "payment" for passage, Lenore agreed that the company would perform Shakespeare's Hamlet for the crew. While the troupe was aboard, Kirk planned to approach Lenore romantically.
With Leighton's death, only two of the nine original eyewitnesses remained alive, and both of them served aboard Enterprise. Lenore first attempted to poison Kevin Riley. She failed because Riley was speaking to someone at the time the poison took effect; help was promptly dispatched. She next hid an overloading phaser in Kirk's quarters, in an attempt to blow him up. This, too, failed; Kirk found the phaser and jettisoned it into space before it exploded.
During the Hamlet performance, Kevin Riley sneaked backstage with the intent of murdering Kodos, the man who had murdered his family. Kirk was able to stop him, but Kodos overheard their sotto voce conversation. Backstage, he discussed it with Lenore – and learned to his horror that she had been, over time, murdering all those who could recognize him, and planned to kill the last two after the performance. Kirk confronted her, and she snatched a phaser from a nearby guard and raced on-stage. Clearly insane, she attempted to kill Kirk, instead hitting and killing her father when he jumped in front of Kirk at the last second. This act destroyed what remained of her mind; she was taken into medical custody. (TOS: "The Conscience of the King")
Lenore appeared again in the novel Foul Deeds Will Rise, when she encountered Kirk while the USS Enterprise-A was acting as the location of crucial peace talks between two planets on the verge of a major disarmament program. Although officially rehabilitated and now working as part of a group of volunteers helping the planet to rebuild, Lenore came under suspicion when two of the delegates- one from each side- were killed in a manner that implicated her; one was killed by the exploding phaser technique that she attempted to use against Kirk and another suffered an overdose of the medication that Lenore was using to maintain her sanity. However, despite the accusations of now-Ambassador Kevin Riley and Lenore's own concerns that she suffered a psychotic break of some sort, Kirk eventually determined that the true killer was one of the delegates attempting to use Lenore as a convenient scapegoat. Although she briefly attempts to hand herself over to the planets' governments to save the conference, once the truth is revealed, Lenore later redeems herself of her past sins by risking her life to destroy a stolen protomatter warhead after the killer attempted to sabotage the Enterprise to prevent it doing so.