Leo tries to convince an unenthusiastic President Bartlet about the merits of an expensive and errant missile defense system while the chief executive ponders the political benefits of chiding hard-core environmentalists over the actions of eco-terrorists when he addresses their convention. Meanwhile, Bartlet endures the formalities of accepting the appointments of a range of foreign ambassadors but he enjoys one in particular — the presentation of the charming Lord John Marbury (guest star Roger Rees, "Cheers") who returns as Great Britain's new U.S.ambassador. In addition, C.J. treads lightly when she is dispatched to New York to dissuade a comedian, Corey Sykes (guest star Rocky Carroll, "Chicago Hope"), who once uttered a well-publicized but offensive joke in the President's presence from performing at the annual Will Rogers dinner.