The Grand Canyon, by Donna Sundling Spagler

Donna sundling spangler was hiking in the grand canyon with her husband, bob. Bob positions donna on the cliff's edge and goes back to mount his tripod. But as he's turned away, setting the timer ah, he hears what he later describes as, quote, a small sound from donna. And when he turns back around, she's gone. Just before noon, bob comes running into the ranger station. His wife has fallen off a cliff.