Volcanologists say the mountain isn’t erupting, yet it’s stirring. The air above the ridge is turning thorny and metallic, a caution flag for pilots and a puzzle for the scientists who listen to rocks. In a place where weather already rules the day, the sky just picked up a new voice.

The first hint wasn’t dramatic. It was a smell—faint, almost shy—like a match just struck and blown out on an icy ridge. A pilot crossing the Aleutians radioed a hazy strip hanging off a lonely summit, not smoke, not weather, something in between. Out on the gravel bar, a field tech rubbed a gloved thumb across a thin yellow smear on late spring snow and didn’t say a word. A satellite pass, then another, traced a ribbon of sulfur above open water. The mountain had gone from silence to a whisper. That whisper could carry.