The speaker is looking for a place of peace, somewhere far enough away that no road is in sight. The opening question, "where am I to look for quiet / and not see a road," sounds half like a real search and half like despair. It suggests that wherever you go, signs of traffic and human travel are already there, and the quiet you want is spoiled before you find it.
The second stanza shifts from the question to an action and a feeling. The speaker walks the fields until dark, as if trying to escape, yet ends up raging "more than ever." The surprise is that the walk doesn't calm them. The mist adds to the mood, blurring the landscape and perhaps the speaker's own thoughts, so the anger seems to swell with nowhere to go. The poem leaves us with restless frustration: the peace of the countryside is wanted badly, and it stays just out of reach.