Magicians Penn and Teller give a controversial performance at Zoey's birthday party in the White House that threatens to drown out the news of the impending China trip. President Bartlet goes to New Orleans on his way to China after unexpectedly requesting briefings be postponed until they are in the air. Josh tries to decide which Democratic presidential candidate he wants to support, and is alarmed that Bartlet wants to appoint California Republican Senator Arnold Vinick to be Ambassador to the United Nations.

President Bartet's attack of multiple sclerosis requires hasty reorganization of the summit in China. Unable to endure the long meetings, he becomes frustrated when the Chinese take advantage of his absence to drag their feet over North Korea. Back at the White House, Josh is told by NASA that a large asteroid is on a collision course with earth; staffers are unsure whether to prepare for the end of the world or not. Donna becomes frustrated when Josh continually postpones what she says is an important conversation. With the New Hampshire primary looming and Vinick looking like a formidable opponent, Josh and Leo try to find a Democratic presidential candidate they can believe in.

On the same day that an anti-gay-marriage amendment is attached to the federal budget, an Internet rumor surfaces that C.J. is a lesbian. Josh and Toby attempt to kill the amendment without forcing the President to publicly take a position on this unwinnable issue. Congressman Santos considers Josh's proposition that he run for President despite having told his wife that he's done with politics. Donna begins her new job while Josh struggles to cope with her difficult replacement. Abby and C.J. meet with the President's doctors to decide how to adapt his schedule to the increasingly debilitating effect of multiple sclerosis.

CJ and Abbey go twelve rounds on how to handle President Bartlett and his disease. Lord Marbury makes his return to the White House after a British commercial plane gets shot down by Iran. Toby splits his time between helping write a Belarus constitution and the yearly meeting with Miss World