He saw no one else in the room, which led him to the inescapable conclusion that the girl was currently behind the mattress.  It was hard to fathom how it could have flown over there, but he’d already estimated that if Lyra could move around marbles with her mind-controlled tractor beam, there was nothing to prevent her from tossing about larger objects.  While the implications were terrifying, he took a vague bit of satisfaction in knowing that he’d guessed correctly.  At the very least, she could pin a woman to the wall with a mattress, and he doubted he’d be able to put up significantly more resistance.