Season 3, Episode 5:

The Cost of Living

In flashbacks, a young Eko steals food for a hungry Yemi, and is forced to confess his sin by a nun. After Yemi is shot, Eko returns to the church in his hometown and takes Yemi's place as a priest. A militia lead by a man named Emeka demand a share of the village's vaccines in exchange for "protection". Eko tries to make a deal to sell the vaccines and flee the country, but it is discovered by the militia, who attack him inside the church. Eko kills them, and the villagers close down the church, considering it desecrated.

On Hydra Island, Jack deduces that the x-ray he saw was Ben's. He admits they had intended to manipulate Jack into operating on him. Juliet privately asks Jack to kill Ben in surgery, and says she will cover for him if he does.

At the beach, Eko sees a vision of Yemi telling him to confess, and goes looking for the beechcraft. Locke, Desmond, Sayid, Nikki and Paulo head to the Pearl, intending to use its computer to help find Jack, Kate and Sawyer. Eko is haunted by visions of Emeka and his gang, and stalked by the Smoke Monster, before he meets the rest of the group. At the beechcraft, Eko finds Yemi's body is missing. The rest of the group search the Pearl, and see a video feed of a man with an eyepatch at another DHARMA Station. Yemi approaches Eko, and tells him to confess, but Eko refuses, saying that he has not sinned, and is not sorry for what he has done to survive. Yemi, disgusted, says "You speak to me as if I were your brother" and walks away. The Smoke Monster appears, and kills Eko, who manages to whisper his final words to Locke. Locke claims that he said that "we're next."

Tropes in this episode include:

• Badass Preacher: Eko, while acting as a priest, curb-stomps the 3 armed militiamen who threaten him in the church.
• Died in Your Arms Tonight: Locke holds Eko as he dies.
• Dying Curse: Although the audience doesn't get to hear them, Locke claims that Eko's last words were "You're next."
• Eye Open: Subverted. An eye opening is perhaps the most common shot on the show, but Eko does not wake up when we see him.
• Foreshadowing:
  • Paulo's reluctance to come to the Pearl and the awkward moment where he startles everyone by flushing the toilet become very significant in "Exposé".
  • Eko's Together in Death flash of himself with Yemi foreshadows the Flash Sideways timeline of the final season, and the reveal that it's an afterlife where the characters find each other and resolve their issues.
• Idiot Ball: Lampshaded. Nikki points out that the point of the Pearl was to observe the other DHARMA stations. Locke admits he's feeling stupid for not realizing that earlier.
• Make It Look Like an Accident: Juliet clandestinely shows a video to Jack in which she asks him to kill Ben during the surgery and make it look like they tried to save him.
• Red Shirt: Subverted. After rumors circulated before the episode indicating that Tonight, Someone Dies, most viewers assumed it would be Nikki or Paulo, given that they were unimportant background characters who had only been introduced a couple episodes earlier. This made it extra shocking when the actual death was Eko, a major character whose story seemed far from over.
• The Reveal: The reason Eko was building the church is because he killed members of an African militia in Yemi's church; the local doctor told him that he now owed Yemi a church.
• Together in Death: After Eko dies, we see a brief shot of him and Yemi walking off together as children with their arms around each other.
• Wham Episode: Eko is killed by the Smoke Monster.
• Wham Line: After Eko refuses to confess his sins to "Yemi".
  "Yemi": You speak to me as if I were your brother.
• You Just Told Me: Jack guesses that Ben is the subject of the x-ray he saw, which Ben inadvertently confirms with his reaction when Jack asks him about it.
  Ben: Why did you show him my x-rays?
  Juliet: I didn't tell him they were yours. But I guess you did.