plumb the depths of something

Từ điển Oxford Advanced Learner 8th

plumb the depths of sth idiom
to be or to experience an extreme example of sth unpleasant
•His latest novel plumbs the depths of horror and violence.
•It was at that stage in her life when she plumbed the depths of despair.
•The team's poor performances plumbed new depths last night when they lost 10-2.
Main entry: ↑plumb_idiom