"I told you, I don't know." Cas' tone sharpened slightly, his patience being, regrettably, far from limitless and having to admit that demons had him at a disadvantage leaving him as close to disgruntled as obedient angels could get (... okay, a little closer than that, if he was being honest).
"Whoever is holding your 'Buffy' does not wish us to know what is happening inside this building. There might be hundreds of them. They might all be on whatever passes for a demonic 'coffee break'. If you would like me to check" – he turned his attention from the building, shooting Dean a glance - “I will oblige. That may, however, remove the element of surprise.”