"It's fine, a simple mista---" He pauses, looking completely distant for a moment, concern coming over his features. He thought he heard knocking....

"I'm sorry, do you hear anything?" He's looking around, searching for a source. "Are you with anyone?"

The strange paranoia of his started when he arrived here, and the nagging feeling had only become worse with each day. Today, every so often, he thought he heard someone knocking.