Reflexes kick in as soon as Book catches the motion coming at him. He swiftly moves back into the edge of the Serenity for cover, and holds up a hand. No weapons, no backup, best bet is to surrender and maybe make them feel guilty for shooting at a preacher. Then figure out what happened to Mal. "Hello? My name..."

He starts to look around to try to figure out what direction it came from, and sees a toy dart sticking out of the hull of the ship. What?

Let's try this again. "Hello?" Except that Book isn't moving out of cover.