Now there's a pile of dust at (and on top of) River's feet, with a crossbow quarrel lying in it.

It's sturdier than River's stick of splintered pine; she ducks, dropping her stake in a puff of vampire-dust and grabbing the quarrel in its place, and whirls back upright to slam it into the chest of the last vampire. His reaction was still in the oh crap stage of indecision between attack and flight; his face changes to a slightly different and more urgent shade of the same expression just before he explodes into nothingness.

And River is left, covered in dust and sweat and alley grime, weapon clenched in her fist, staring fiercely at the blond woman facing her.