I climb steadily for the first hour, zigzagging up the side of the hill, keeping the chalky line of the road in the corner of my eye. Climbing isn’t so easy in spring as it is in winter. Plants and shrubs are sprouting everywhere and, wary of lethargic snakes and even warier of the spiky cactus cities dotted around underfoot, I keep my eyes glued to the ground, so much so that when I reach the cliff edge I nearly step straight off into the abyss. I walk along the spine of the mountain until the belt of oaks below me swings far to the right, then scramble down and set off again. I can no longer see the road, but according to the compass it should now be directly south.

Distance is misleading. It plays tricks on you. The sun, the heat, the sheer scale of the surroundings all conspire to swindle you out of your sense of time and perspective. I had figured on reaching the road within a couple of hours, three max, but after a further hour of flat hiking, I seem to be no closer. Uneasily, I check the compass, then shake it disbelievingly. Somehow I’ve lost due south and now appear to be heading west, with no way of judging how long I’ve been off track. It’s getting hot and my backpack is rubbing against my shoulders. I stop and drink some water, shielding my eyes from the sun and for an instant, sensing that I’m being watched, check the immediate bushes, but there’s nothing out here. Just a great stretch of rock and scrub. The landscape is empty of people, apparently empty of threat, but of course that, too, is just an illusion. Even with the glitch in direction I can’t be more than a few miles off the Mexican border and where there’s a line there will be people crossing it. At any moment our paths might meet and how safe will I feel then? Still, I bolster myself with the thought that this is merely a hike. No different from any other I’ve been on over the last few months. Just because it’s a hike with intent shouldn’t make it any more dangerous. I hitch up the backpack, correct course and press on.