to directly attack the enemy's headquarters or capital, specifically referencing the Jin dynasty capital Huanglong

岳飞誓要直捣黄龙，迎回被俘的二圣。

idiom · to deal directly with the core or source of a problem or the enemy's vital point

要解决目前的危机，我们必须直捣黄龙，找到幕后主使。