Their purpose was to steal the trilithium resin, an extremely unstable byproduct of warp travel that accumulated in the ship's engines. The team first masqueraded as maintenance workers until they believed that the Enterprise had been deserted for the sweep. Kelsey soon put her plan into motion, deploying her fellow team members Neil, Satler, and Pomet to the warp core to collect the resin and assigning Kiros and Devor to patrol the ship. Unknown to her, Captain Jean-Luc Picard had returned to the Enterprise, looking for his saddle that he had left behind.
As the team prepared to extract the trilithium from the core, their plan began to fall apart when Captain Picard subdued Devor. Kelsey grew suspicious when Devor dropped out of contact, and her assigned Kiros to locate him. Kelsey oversaw the extraction of the trilithium and was soon met by Kiros, who had captured Picard. However, Picard pretended to be the ship's barber, Mot, in order to avoid suspicion. He was successful in damaging the main transport module that they had prepared for the trilithium, as well as killing Satler, and Kelsey began preparations to move the resin to Ten Forward, the last place to be hit by the sweep. After locating a communicator left by Picard, she contacted him, realizing that he was a Starfleet officer and trying to convince him to give up. At the same time, she assigned Pomet to track down Picard, although Picard outsmarted him and subdued him.As the team moved to Ten Forward, Kelsey confirmed that Neil had successfully secured the trilithium for transport, and soon killed him, no longer needing his services. Picard was soon captured again by Kelsey and Kiros, and revealed who he was, offering himself as a hostage in exchange for the trilithium. Kelsey then revealed that she and her team were not terrorists, but that they instead intended to sell the resin to the other parties. Picard ultimately outsmarted Kelsey and Kiros in Ten Forward, leading them into a trap that knocked Kiros unconscious. Kelsey and Picard fought, and he succeeded in removing the stabilizer from the transport module. Kelsey, believing that she had succeeded, beamed aboard her ship with the resin, not realizing that it had been destabilized. Kelsey was killed when the trilithium she was transporting to her starship exploded. (TNG: "Starship Mine")