The Lights of Zetar

The Enterprise is taking Lt Mira Romaine to Memory Alpha, the Federation's central library, and Scotty has fallen for her. On the way, a storm moving at warp speed passes through the ship, affecting the crew, and Romaine collapses. The storm then strikes Memory Alpha, destroying its records and killing almost everyone there. Romaine has visions of these events before they happen. Spock concludes the storm is made of living beings, and when Kirk attacks it with phasers, Romaine cries out in pain. McCoy finds her brain patterns now match the storm. The lights enter her body and speak through her: they are the last life forces from the dead planet Zetar, seeking a body in which to live again. Scotty forces Romaine into a pressure chamber, where the extra pressure drives the Zetarians out and destroys them. Romaine recovers and is assigned to help rebuild Memory Alpha.