The Tf141 had tracked a hacker, a black hat, that had stolen/given Intel to Makarov. Intel that led to deaths of many. The mission was to get to the hacker, hoping this way they could get info on Makarov

That hacker was tracked back to a school. So Ghost gave snipe support while the rest of TF141 disguised themselves as teachers

But it went all wrong as he entered an empty classroom, then being knocked out. As he woke up, he found himself restrained against a chair. Just like Price and Soap