River's reflexes are fast, right up at the limits of human capability, and her talents give her an extra few seconds' warning. But she's still only human, gunslinger or not, and Carlisle's speed is well into superhuman.

His hand hits, a sharp marble-hard strike, before River's barely begun to flinch away, and it knocks her sprawling across the table.

(For an instant, as she slams against wood, there's a hard lethal glitter in her eyes that any predator would recognize.)