The familiar ridge won't stay still under my hands

I'm guiding a client up a limestone ridge I've climbed maybe two hundred times, and the rock feels warm to the touch — not sun-warm, but like it's been holding a body. The cairn at the top is gone and I can't find the descent. I keep pointing at the next handhold and my hand is pointing at empty air. The silence up there is the same silence, but it's listening now.