In September 2002, four members of Congress met in secret for a first look at a unique CIA program designed to wring vital information from reticent terrorism suspects in U.S. custody. For more than an hour, the bipartisan group, which included current House Speaker Nancy Pelosi (D-Calif.), was given a virtual tour of the CIA's overseas detention sites and the harsh techniques interrogators had devised to try to make their prisoners talk. Among the techniques described, said two officials present, was waterboarding, a practice that years later would be condemned as torture by Democrats and some Republicans on Capitol Hill....