Above Lolo Pass, on what used to be US Highway 12 on the Idaho-Montana border, a young woman is lying flat on her stomach in the snow, raven hair tucked up carefully inside a white ski mask. She's wearing drab gray wool pants imported cheap from Switzerland, and a tan Columbia ski jacket with buttons sewn on in front; the zipper died a couple of years ago. Her most prized garment, though, is a white fleece blanket spread over her whole body. A flurry of snow covered her in icy powder a few hours before dawn. She's almost invisible from the air in all spectra.

The first time she did this, she had a pocket full of chocolate bars to keep her sugar up, and a little thermos of coffee to keep her awake. She hasn't even seen chocolate since summer before last, and then she didn't eat it herself. She closes her eyes against the glare as the sun rises over the hills in front of her.

In these early mornings, when the cold's so bad, she thinks about her old life. Piano lessons, dancing. A huge flag, illuminated by a spotlight, fluttering in the night wind at the supermarket: the most beautiful thing she can remember. She never sings out loud anymore, but she still thinks music.

A rumble in the distance brings her fully alert. She rolls to one side just enough to extricate the rifle from underneath her body, and gently slips a plastic bag off the muzzle. It's a Remington .30-06, the last one rescued from a Wal-Mart in Missoula five years ago, painted white the next winter. She pulls one glove off with her teeth, works the bolt and eases the weapon to her shoulder. Just a couple of minutes before the convoy rounds the bend.

America's last war is very cold.