An energy storm of unknown nature attacks Memory Alpha, killing the inhabitants and destroying the Federation's central library facility. After a chase, it then enters the Enterprise and possesses Lt. Mira Romaine. The 'lights' refuse to leave her mind and body, insisting that they have a right to live, even at the expense of Mira's life. After being placed in a decompression chamber, the 'lights' leave her.
A fairly run-of-the-mill episode.
A fairly run-of-the-mill episode.