In 2369, Tallera infiltrated Arctus Baran's raider. She confided in Jean-Luc Picard who also had infiltrated the mercenary ship, that she was a Vulcan agent of the V'Shar sent to find the Stone of Gol. It amplified telepathic energy and if used by a trained telepath, it became a powerful weapon that could kill. An isolationist group on Vulcan was seeking the weapon to overthrow the planet's government.
In reality, Tallera was a member of the isolationist group and upon finding the pieces of the Stone of Gol (a psionic resonator), assembled it and killed the mercenaries in the T'Karath Sanctuary on Vulcan. Picard however had deduced from markings on the stone that it could only kill by using aggressive energy of the victim. By clearing his mind of violent thoughts, he was able to disarm Tallera and arrest her. (TNG: "Gambit, Part I", "Gambit, Part II")