The policeman got a stool pigeon. That is why he can always get the first-hand information.

那位警察有个密探。这就是为什么他总有第一手消息的原因。

Watch out for John; I'm sure he's a stool pigeon for the police.

提防着约翰，我敢肯定他是警方的眼线。

The "King of Stool Pigeon" sneaks into a girl high school to investigate the daughter of an underworld leader, and found other illegal activities in that school.

警方「卧底之神」哪吒受命潜入女子高校，调查江湖人物之女，却意外发现黑帮活动。

As a lawyer, how could you believe a stool pigeon ?

做为一个律师，你怎么能相信一个假证人的话呢？