This episode's headline: Securing the Homeland; The Liability of Terror; Case for Clemency; Conversation;. ANCHOR: JIM LEHRER; GUESTS: DEBORAH BECK; TRAVIS PLUNKETT; MARK SHIELDS; DAVID BROOKS; DIANA WALKER;CORRESPONDENTS: KWAME HOLMAN; RAY SUAREZ; SPENCER MICHELS; MARGARET WARNER; GWEN IFILL; TERENCE SMITH; KWAME HOLMAN