At the center of a diamond formation of Secret Service agents, Ronald Reagan stepped from the secure VIP exit of the Washington Hilton and onto the damp sidewalk. When a small crowd yelled greetings from across T Street, his movie-star smile instinctively materialized. 

The new president crossed the pavement to a Lincoln parade car and heard the familiar voice of ABC White House correspondent Sam Donaldson rise above the din: “What’s the latest on Poland, Mr. President?”

Reagan merely turned toward the press line and waved. 

Next to Donaldson, a 25-year-old man in a trench coat flexed his knees and raised his hands in a marksman’s stance. With a revolver he had purchased at a Dallas pawnshop, John W. Hinckley Jr. fired six shots. 

It was the 70th day of the Reagan presidency. ...