Steadying himself by one hand on the low rail, Dunn drew his revolver with the other.

"Sing out to him to pull up, or we'll fire.

My voice is clean gone," he added, in a husky whisper.
They were so near that they could distinguish the bulk of a vehicle careering from side to side in the blackness ahead.

Dunn deliberately raised his weapon.

"Sing out!" he repeated impatiently.