Lesser Evil
Lesser Evil is a Pocket DS9 novel – part of the  and the fourth novel in the Mission Gamma series – written by Robert Simpson. Published by Pocket Books, it was first released in .

Summary 
From the back cover
SINS PAST

Chaos erupts aboard Deep Space 9 as the crew begins a desperate search for a killer in their midst, catapulting Colonel Kira Nerys on a dangerous chase into the heart of the Federation. But the crime she seeks to avenge is part of a plot more ancient and far-reaching than anyone suspects, and that secret, if exposed, could divide worlds throughout the Alpha Quadrant.

Meanwhile, as the Starship Defiant makes its way back toward the wormhole and home to DS9, a startling discovery shakes Commander Elias Vaughn to his core and brings to light the truth behind the most tragic mission of his long life. As the crew struggles with the implications of what they've found, their captain's judgment comes into question… and casts doubt on the final outcome of their historic voyage through the Gamma Quadrant.

Ruriko Tenmei 
After catching a Starfleet distress signal, the crew of the , still in the Gamma Quadrant, lands on a planet and finds an old starship – one that has been completely assimilated by the Borg. Elias Vaughn finds out what has become of his wife, whom he thought was dead: Ruriko Tenmei, mother to Prynn Tenmei, has been assimilated and is now a Borg drone. Julian Bashir tries everything to revert the Borg's alterations, and Prynn tries to assist as best as she can. After a long talk Vaughn has with Ezri Dax, in which she makes clear to him that he has to report the events they encountered, namely the presence of a Borg ship in the Gamma Quadrant, Vaughn finally accepts this and tells Dax about the situation in which he sent his wife to her death seven years ago – a decision that diverted him from his daughter.

While bringing another Borg drone aboard, this one already dead, its nanoprobes all of a sudden come to life; it becomes clear that, even if the drone is long dead, the technology still works. Vaughn, fearing for his daughter's life, runs to sickbay, only to see that the drone formerly known as Ruriko is too close to Prynn – and after Prynn backs away, seems to start chasing her. Protecting his daughter, he kills the drone, leaving Prynn devastated.

Ezri later tries to explain to her what her father did, deliberately holding back some of Bashir's findings, namely that there could have been a chance to save Ruriko; Prynn believes that the Borg's alterations had destroyed her brain too much to reverse the process. Still, she is not sure whether she could ever forgive his father for taking her mother again.

The Changeling and the Borg 
On the same planet they found the Borg vessel, the crew also finds a Jem'Hadar vessel; the two ships obviously having fought against each other, leaving both damaged on the planet. Nog and Shar detect a Changeling aboard the Jem'Hadar ship, obviously still alive. They manage to contact her (it has the form of a girl), and explain about the changes that happened during the last two years, in which the Changeling was alone on the planet: the end of the Dominion War, the new situation with Odo and the presence of Taran'atar on DS9. The Changeling agrees to come aboard the Defiant.

On the ship, the second Borg drone tries to assimilate the Changeling – but since Changelings do not have cellular structures, it fails.

The chase to Trill 
After the murder of Shakaar Edon, the USS Gryphon is sent to Trill, and Kira Nerys is ordered aboard. On DS9, the medical staff finally discovers that Shakaar was under the control of a parasitic being and was obviously killed because of that. It becomes clear that someone aboard the Gryphon must be under the control of one of these parasites as well. After talking to First Officer Montenegro and Admiral Leonard James Akaar, who relays the recent findings, Kira is convinced that Captain Elaine Mello is the person in question &ndash only to find out that in reality it was Montenegro, who then tries to bring the ship under his control, killing Mello in the process.

Mello, before dying, transfers the command of the ship to Kira; the Bajoran colonel finally manages to kill both Montenegro and the parasite, and thus prevents the starship from approaching Trill and assaulting the planet. Kira is contacted by a Trill admiral who promises to tell her everything about these events – claiming that the parasites' target are the Trill symbionts.

Joseph Sisko 
Joseph Sisko is still in very bad shape, when Kasidy Yates finally has the idea of contacting Miles O'Brien and his family. They arrive at Sisko's house, and the effect Miles, his wife Keiko O'Brien and especially his kids have on Joseph is marked: the old man is rejuvenated, and begins to accept the events that left him so depressed. He then decides to travel to Bajor, to see Kasidy and to be present when his grandchild is born.

Return of the Defiant 
Finally, after their long mission, the Defiant heads for DS9. When they arrive at the wormhole, they find that their communications relay is destroyed, and that the Idran system all of a sudden has shifted position – now located at the mouth of the wormhole. While investigating, the crew is contacted by a Jem'Hadar ship. A Weyoun 9 clone requests the Changeling they have aboard, and in return beams three passengers they have picked up to the Defiant: Kai Opaka, an alien named Wex, and Jake Sisko. Jake says to his stunned friends that he has a long story to tell…

Background information 
 This is the only full-length Star Trek novel by author Robert Simpson. It was based in part on a pitch Simpson and Pocket editor Marco Palmieri developed for the television series, in which Jennifer Sisko would have been the recovered Borg drone. ()
 Kora II is listed on the title page as the location of one of Pocket Books' offices.
 Cover by Cliff Nielsen.

Characters

Regular and recurring characters 
Kira Nerys  Kira's Starfleet commission is reactivated by Admiral Akaar.
Elias Vaughn  Starfleet commander, the CO of Defiant.
Prynn Tenmei  Ensign aboard DS9, daughter of Elias Vaughn
Julian Bashir
Ezri Dax
Sam Bowers  Tactical ops
Kasidy Yates
Miles O'Brien
Keiko O'Brien
Molly O'Brien
Kirayoshi O'Brien
Nog  Chief engineer on DS9
Quark
Ro Laren  Chief of security on DS9
Joseph Sisko
Judith Sisko
Leonard James Akaar  Starfleet admiral.
Charivretha zh'Thane  Andorian member of the Federation council, zhavey (mother) of Thirishar
Lenaris Holem
Thirishar ch'Thane  Ensign aboard DS9 and the Defiant
Girani
Gul Macet  Captain of the Trager
Opaka
Madred
Asarem Wadeen  Bajoran first minister
Elaine Mello  captain of the Gryphon

References 
Borg  The Borg knew about the Gamma Quadrant and were interested in the Dominion and the Changelings; however, the acquisition of this new knowledge collided with their war with Species 8472, resulting in a shift of priorities.

Alpha Quadrant; Andorian; Bajor; Bajoran; Bajoran wormhole; Capella IV; Capellan; Cardassian; Cardassian Union; ; Deep Space 9; ; Dominion; Emissary of the Prophets; Ferengi; Ferengi Alliance; Ferenginar; Founders; Gamma Quadrant; Grand Nagus; Great Material Continuum; Jefferies tube; Jem'Hadar; kai; Klingon; Ktarian; Morn; Orion Syndicate; Portland; Prophets; Rom; Romulan; San Francisco; Shakaar Edon; ; ; ; ; Starfleet; Starfleet Academy; Tellarite; Trill; Trill (planet); United Federation of Planets; ; warp core; Tzenkethi

External link 
 

cs:Lesser Evil
de:Das kleinere Übel
Novels