The twins are in bed when it happens. They hear a sound like a wet cabbage hitting the wall. Then a clattering on roof tiles. Followed by a tapping at the window. It's a girl. With a broken wing. And she's here to stay.

Who is she? Where did she come from? And, more important, what does she want? The twins have no idea.

Perhaps she's their guardian angel.

But would an angel have filthy feet? Would an angel...snore?