third degree
noun /ˌθɜːd dɪˈɡriː/
  /ˌθɜːrd dɪˈɡriː/
[singular]Idioms Idioms 
give somebody the third degree 
- (informal) to question somebody for a long time and in a careful and detailed way; to use threats or violence to get information from somebody对某人逼供(或疲劳询问、刑讯)