In 2015, Craig McNamara — the son of former defense secretary Robert McNamara — got in touch with Rich Rusk, son of former secretary of state Dean Rusk. They had a lot in common. Their fathers had been chief promulgators of the war in Vietnam. Both sons had opposed the war. Both loved their fathers desperately, although Rusk once refused to speak to his for 14 years. Both had gone off the grid for extended periods of time — Rusk, salmon fishing in Alaska; McNamara, traveling and, for years, subsistence farming in South America. They talked about visiting Vietnam together, but they never made it. On Jan. 28, 2018, Rusk killed himself by jumping off a bridge.