C52 Mysterious wellhead (2)

I asked what the noise was about. We all heard two rhythmic knocks, then a pause, then two rhythmic knocks, all the way back and forth for thirty times, and then it was over.

"Ah, we don't know about that voice. In any case, this place would be beaten thirty times every hour, which was also a combination. But I say, how do you know the secret of this place? " The boss looked at Qing Er in shock