"What now...?" Song Lei muttered to himself.
He was inside a well-lit corridor. While one side of the corridor had five distinct sliding doors that probably led into other classrooms, the other side was covered in windows that were, just like the ones in the classroom, fully blacked out.
He had an immense urge to go ahead and open one of the windows. However, an instinctive fear prevented him from doing so. He felt like the darkness would start spilling into the corridor and capture him.
Not knowing what to do, Song Lei took another look at his backpack. Interestingly enough, there was something that wasn't there before.
It was a notebook with a blue cover. There were at most fifty pages inside it, making it very light. As Song Lei pulled it out, something fell out of the notebook.
It was a single key with a tag attached to it. The number '1407' was written.
'Great...'