But he didn’t reply. His attention snapped toward the cave entrance, his senses sharpening. A low, steady rumble vibrated through the stones, like distant thunder, but too even, too mechanical. River stiffened, every nerve on edge.

“Stay here,” he ordered.

“Wait... what? River!”

But he was already running toward the mouth of the cave, his black hair the last thing she saw before she scrambled after him, confused by his sudden alertness.

When she finally reached the entrance, gasping, her aching