Dr. Mara Venn got the call before sunrise. A cliff face had collapsed above a remote bend of the Colorado River, miles from the main trails and the more crowded overlooks. By the time Mara reached the rim, dust still hung like a phantom mist in the canyon air. Far below, a river guide stood beside his raft, pointing up at a fresh, jagged wound in the ancient stone.
“It just sheared off,” the guide’s voice crackled over the radio, tight with awe. “One minute it’s solid wall, the next, half the cliff is in the river. You’ve got loose blocks balanced up there like dominoes.”
Mara raised her binoculars, adjusting the focus. At first, she saw only the predictable chaos of a rockfall: fresh fractures, broken ledges, and streams of talus sliding down the wall. Then, her view settled on a dark gap halfway up the cliff. It was a sharp, geometric shadow. Too straight to be natural. Deep inside the void, something metallic caught the morning sun and flashed…