devices in the office, and they captured hundreds of hours of history-making decisions and moments in his family life. >> now the new book has details of those conversations. diane sawyer has more. >> i remember really clearly being under the desk and making necklaces and trying to get candy from the grown-ups who were around. >> reporter: caroline kennedy says it's wonderful to hear him laughing when she walks in, demanding attention. >> i won't let you do much. >> reporter: that sound is little john, pounding under the desk, no idea he's hitting a microphone. his father, just relaxed. >> it was really like being in his company while you're listening. that was really a wonderful feeling for me. >> reporter: what you hear on the tape is a man possibly calm in a crisis. intelligence discovered the soviets placed nuclear missiles inside cuba, aimed at the u.s.