At this time, Liang Chao wondered why the sound would appear at the stairway every time, just like the signal. What is its purpose? Is it to attract them to the past? Still, inform the people on the next level that the police have arrived.

However, this is just Liang Chao's guess. Their real role is not sure. So, he took people with him and continued to search on the ninth floor.

the police station building is divided into ten floors. Starting from the seventh floor, there are conference rooms and spare rooms that have not been used yet, so almost no one is there. Even some people, after two...