After the hunter exams where Killua was disqualified he went home you Gon Kurpika and Leorio went to the Zoldyck family estate to find him you saw the guard dog Mike and went to a house to stay in the night before going back to him but little did we know he in the torture room in the basement getting whipped but it didn’t hurt him he could easily break off the chains that he voluntarily went in

Gon: “I won’t stop til I get Killua back he was our best friend we can’t just leave him.”