If you're of a certain age, you remember where you were when something big and historical happened. For my parents, it was Pearl Harbor. For my children, it was the Challenger explosion. For me, it was the John F Kennedy assassination, on Nomb 22, 1963 in Dallas, Texas.

But in the intervening decades, members of the president's Secret Service detail rarely spoke about that day, even among themselves. That changed in 2010, when Gerald Blaine, a senior member of the detail, wrote a book about their common experience.