Contains spoilers for this episode and earlier episodes.
President David Palmer learns that terrorists have a nuclear weapon in Los Angeles and intend to detonate it that day. CTU wants Jack Bauer to return because one of his old undercover contacts may lead them to the attackers. Jack is still grieving Teri and living apart from Kim, who says seeing him reminds her of her mother's death. He initially refuses to help, but Palmer calls him personally and persuades him to hear the briefing.
At CTU, Jack demands that trusted personnel take Kim out of the city before he agrees to work. George Mason identifies Joseph Wald as their best connection to Second Wave, the group suspected of planning the attack. Jack once worked undercover with Wald and helped imprison him. Learning that Marshall Goren is the key witness in Wald's new case, Jack orders him brought in, shoots him and requests a hacksaw to prepare his return to that cover.
Kim is working as Megan Matheson's au pair when Gary's violence turns a morning at home into a threat to both of them. He shoves Kim and injures Megan against the bed. Elsewhere, Kate Warner worries about her sister Marie's approaching marriage to Reza Naiyeer. A private investigator tells Kate that Reza may have dealt with Syed Ali, a financier linked to terrorism, and asks for her help checking the connection.