A speaker stands on a ridge and watches cloud shadows move across a valley full of snow. The title, "Filmstrip," fits: the light flickers between "gloom and glare" like frames passing in a projector, and the speaker is held by it, almost hypnotized.
The most striking moment is the comparison in the first stanza. The shadows drag across the snow "as if dragging for a drowned swimmer," as though the valley were a lake being searched after a death. That image gives a calm, beautiful scene an undertone of loss and unease.
The last stanza brings in signs of human and animal presence. A "No Hunting" sign rattles in the wind, while below it are the "deep claw-marks of bears." The sign tries to impose rules, but the claw-marks suggest wilder forces that ignore them. The mood is quiet, eerie, and watchful: the speaker seems more awed than afraid, simply taking in a landscape that is both lovely and a little menacing.