プログレッシブ和英中辞典(第4版)の解説
ごりむちゅう【五里霧中】
山中を五里霧中で歩き回った
They wandered through the mountains, totally lost.／They completely lost their bearings and wandered around on the mountain.
研究方法も分からず五里霧中だった
He was 「at a complete loss [completely in the dark] as to how to proceed with his research.