Star Trek: Deep Space Nine: Fearful Symmetry

Sixteen years after the failure of a plot to replace Bajoran resistance fighter Kira Nerys with a Cardassian sleeper agent, Iliana Ghernor, surgically altered to resemble Kira, a vengeful Ilian Ghernor returns determined to destroy her rival, while the crew of Deep Space Nine must protect the flow of history through two parallel universes. Original.