The library was essentially silent, and Barty's steps led carefully around row to row. His eyes peered carefully around a corner before he came around. And his wand was up, at the ready. His progress was slow but steady. After all, it was quite possible more than one person was there, and while his nerves were alive, and he was a risk taker, Barty was very good at his job, and he did it seriously.
There was a sound, faint and quiet. Barty stopped in his tracks for a moment. He heard another noise, very faint, but it sounded...that wasn't a voice. And it wasn't...a book. It was...Barty moved toward the front of the library, but by the time he got there, no one was there. He kept to the edges though, disliking the open - it made him feel exposed. And he was confident, not stupid. Held the job too long. Well, his search continued, checking out each row.