The poem reads like a memory caught in a flash: two people, dressed in bed sheets as a sort of ghost costume, sneak past a sign put up by the "summer people" that says DO NOT ENTER. The disguise is a poor one, and that adds to the playfulness. They are breaking a rule, but gently, the way people do when they're young or feeling young.
The setting has a haunted edge. Burnt spruce trees line the clay road and seem to look down on the pair, and the two climb toward a place that already feels familiar. In the last stanza the speaker suggests circling the rose-colored farmhouse in silence, three times, as if repeating a ritual. The shuttered windows are "left longing," which makes the house seem lonely, almost waiting.
The mood mixes mischief with nostalgia and a quiet sadness. The speaker seems to treasure this shared trespass, and the empty house mirrors the feeling of something once lively now shut up and wistful.