The men in the detail turned serious only when we passed through a tunnel. “I hate tunnels,” one growled tensely. “Why?” I asked. “Everything bad happens in tunnels,” he said. “We learned that in Iraq. They can block you in on both sides and do anything they want to you in the middle,” he explained. He only began to relax again when we emerged safely on the tunnel’s other side. “Everything bad happens in tunnels,” I thought, reflecting on the past four years, Facebook’s single-minded race to domination, and every strange, churlish thing that happened that I just had to shake off, because I was trapped in the middle and had to get through to the other side.

I like these security guys, I thought. It seemed healthy to be hanging out with people who had fought in real wars.