Read a spoiler that basically the adventurer's guild of that city is corrupt, so much so that they break the law of the government, it goes bad for them when his former party fails a conquest and the monster goes into a rage (which requires reporting to the government/guild leader because enraged monsters get stronger, leave the dungeon and attack towns, they don't report it because it would look bad on them and it would get the leadership involved), when the monster get's out, the corrupt guild lady shown in ch 2 being the big one, get's removed from her position, and the 2 asshats in his former party are on the run with warrants out for their arrests, the 2 innocent members don't get charged i think but not sure (might end up being part of the mc's party later but the raws aren't far enough for me to make a guess).