Off the hook means to be free of blame, or to be free from a difficult situation. Consider the following examples :
" I know you didn't steal the money Tom because David confessed to the crime, you're off the hook."
" I got in two hours late last night, but thankfully my parents didn't hear me. I'm off the hook!"
"Even though I handed my homework in late, my teacher let me off the hook with just a telling off."
Hope this helps with your understanding of this interesting phrase!
Deborah ESL :-D
Interested in Language