Catalyst of Sorrows (Star Trek: The Lost Era, 2360)

THE YEAR IS 2360
She was trained to be a killing machine. Abandoned as a child, without home or family, past or future, Zetha survived only by her own cunning in the back alleys of Romulus before being taken by the Tal Shiar and remade into one of its deadliest weapons. But Zetha is about to undertake a mission unlike any in her experience.
The mysterious return of a virulent scourge thought to be long extinct threatens devastation on a scale almost too horrific to contemplate. Zetha's only hope of stopping it is across the Neutral Zone -- among the enemies of Romulus. Now Admiral Uhura, centenarian chief of Starfleet Intelligence, must decide what to do with the knowledge Zetha has risked her life to bring to her. In order to stop the spread of the disease that is already ravaging the Romulan Empire, Uhura must assign a hand-picked team of Starfleet officers to covertly trace the contagion to its source -- and do whatever is necessary to contain it.
But the world awaiting Lieutenant Benjamin Sisko, Lieutenant Tuvok, Dr. Selar, and Zetha herself is a hot zone of secrets, deceptions, and subtle machinations revealing an imminent holocaust beyond anything the away team expected, or what they could hope to combat.