Keller opened the drawer. “Pick your poison,” he said with a grin, several days of stubble giving his chin a ragged look.

Undaunted, Polly reached for the largest knife, all gleaming metal, almost a foot long. She stepped back and echoed Keller’s grin, but with a single laugh and a slight sheen of sweat on her upper lip that gave away her nervousness. “Okay. What now?”

Keller’s grin faded. “What the hell is that?”

”What?” Polly said, looking down at the knife. It looked big and sharp and inti...