Part of the adventure in luring your friends out to the high desert terrain in Northern California, where a valley floor spills from the northern backside of Mount Shasta, is that precious moment when they look at you as though you’ve led them into danger. Having discovered Pluto’s Cave from a map, I was prepared for some sagebrush whacking. What I wasn’t prepared for was that reaching the trailhead required navigating a maze of dusty roads. The cave is considered an easy hike — no serious spelunking experience necessary — and located less than 20 minutes from Interstate 5. Pluto’s...