"I'm here!" he calls over the rushing water. "Morgana, take out your sonic and use it as a torch!"

He says the word in his natural language that means 'electronic lighting device', and he thinks he might need to reword. But no, no, the colloquialism should make sense to her, too. He worries about his own sonic and the things he has in his pockets, but he can't fret about them. He's got to move the bookshelf.

But where? It's so utterly dark in the room.