Spoilers for this episode and earlier episodes of Lost.
Daniel, Charlotte and Miles are captured by people wearing American military uniforms on the island in 1954. Richard believes they have returned for a hydrogen bomb left by the army. Daniel uses that misunderstanding to secure permission to inspect it, arguing that its damaged casing threatens everyone nearby. Ellie escorts him to the bomb, called Jughead, where he recommends sealing its leak and burying it rather than trying to move it.
Elsewhere, Juliet recognizes Latin spoken by Sawyer and Locke's prisoners as a language used by the Others. One prisoner kills his companion and escapes; he is revealed as the young Charles Widmore. Locke follows him to Richard's camp and presents the compass Richard gave him during a later period. Richard does not recognize Locke, so Locke provides his future birth details and asks Richard to visit him. Another flash interrupts their conversation, and Charlotte collapses after the group escapes its captors.
The mainland story follows Desmond searching Oxford for Daniel's mother, after an earlier scene shows Penny giving birth to their son. The university denies any record of Daniel, but Desmond finds his abandoned laboratory and learns about Theresa Spencer, whose condition followed Daniel's experiments. Theresa's sister says Widmore funds her care and financed the research. Desmond confronts Widmore, who supplies an address in Los Angeles. Penny agrees to accompany Desmond there, despite their wish to keep their family away from the island.