the.com/firing line

means The position of direct exposure to criticism, blame, or consequences — the spot you occupy when things go wrong and people start looking for someone to answer for it.

from Literally a military term: the line soldiers stood on, shoulder to shoulder, to shoot at the enemy — meaning it was also the line the enemy was aiming back at. By the late 1800s the phrase had leaped from the battlefield into general use, keeping its sense of being exposed to incoming fire, except now the 'fire' is usually questions, blame, or an angry boss rather than bullets.