Isaac hung around with the wrong crowd and I'm afraid for him because he's in too deep now. (*) in the deep end of the pool (*) underground (*) seriously and deeply involved
This is a companion discussion topic for the original entry at https://english.best/questions/23890,isaac-hung-around-with-the-wrong-crowd-and-im-afraid-for-him-because-hes-uin-too-deepu-now/