Part 1: And so we set off, struggling under our packs, into the Smokies, so named because you rarely see the sun through the fog – off, as my granddaughter Calliope likes to say, on an adventure.

You run into some odd people on the Appalachian Trail (when, that is, you run into anyone at all). My daughter Gayley and I once shared a shelter with two women who were through hiking from Georgia, and we occasionally met someone heading in other direction, but for the most part we had the trail to ourselves. Until the second-to-last evening when we got to our shelter later than planned and found only two sleeping spots left on the hut’s second tier. Climbing the ladder I came face to face with a man sitting silently, who met my jovial, “Hi!”, with a glower that looked right through me. It’s a stare I have been unable to forget.

No way I’m sleeping next to that guy, I thought. My paternal sense of duty belatedly prevailed, however, and I warily put my pack between his sleeping bag and my daughter. After eating our simple supper, all the while watching this man scrounge food from other hikers, we settled in for the night. AT shelters have chain-link gates with padlocks, and just before we crawled into our sleeping bags my bunkmate announced that bears had been spotted in the area and locked the gate. Now, I thought, we can’t get outs.

Many years ago, in a remote Maine house in late fall, I read Helter Skelter, Vince Bugliosi’s terrifying account of the Manson killings, and I’ve never quite recovered. Shortly before dawn I heard, next to me, a click, which I recognized from my days in military intelligence as the unmistakable sound of a clip being loaded into an automatic pistol.