"The Collaborator" is the 44th episode of the science fiction television series Star Trek: Deep Space Nine, the 24th episode of the second season.

Major Kira finds herself investigating Vedek Bareil when pursuing allegations made by a Bajoran banished from his homeworld for helping the Cardassians during the occupation.

The Bajorans are about to select a new Kai, the supreme religious-leader of all Bajor, now that the popular and respected incumbent Kai, Opaka Sulan, is gone. Kira had hoped to see Vedek Bareil become the spiritual leader of Bajor, but he is running against a formidable opponent: Vedek Winn. Major Kira has recently started a romance with Bareil. She loathes Vedek Winn, both for her politics and her personality, and has a strong suspicion she is responsible for a recent assassination attempt on Bareil.

Meanwhile, Odo has arrested a Bajoran man called Kubus Oak, who has been exiled for collaborating with the Cardassians during their occupation of Bajor. Vedek Winn relieves Odo of the criminal and offers Kubus sanctuary in exchange for information about the Kendra Valley Massacre that occurred on Bajor during the war. The massacre claimed the lives of 43 Bajoran militia-members (including Opaka's own son), and it is rumoured that it was a Vedek who tipped off the Cardassians. Winn is eager to find evidence that this Vedek was Bareil. Winn gloats to Kira that she is about to ruin Bareil's chances for becoming Kai.

The crew analyzes some records and the evidence is there: Bareil was responsible. In disbelief, Kira confronts him. He admits to being the Vedek who provided the Cardassians with the location of the militia. He then explains that if he had not done this, the Cardassians would have destroyed village after village until they were certain they had wiped out the militia. Bareil gave them the information to save a thousand villagers, at the cost of the 43.

Kira is crushed. Soon after, she hears that Bareil has withdrawn his nomination for Kai, clearing the way for Winn to take the post. With further investigation, Kira makes another confusing discovery: proof that Bareil was not the source of the information. He had covered up for someone else. When she asks him about it, he admits to her that it was the revered Kai Opaka who had been the "collaborator". She had sacrificed the militia, along with her son, to save the villagers. Bareil had covered for her, because the Bajorans needed to believe in her during this painful time in their history.

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