"Arboga emptied." The woman's voice drops beneath the guard's footfall. Her eyes stay fixed on the mushroom. "Not in a day — a fortnight. The ones who stood nearest went first. Sores behind the ears, fever that climbed and didn't come back. The colour of those spots." Her chin tilts toward the rust-flecked cap. "My mother survived because her father ran the moment he heard the hum — pulled her from half her family still standing in the square." The guard's hand settles on the sweeper's shoulder. "Different shape," she says quickly. "Same sound. She made me promise: if you ever hear it, do not walk toward it." Her mouth pulls tight. "I heard it before I reached the first stall this morning." The boy at her hip watches the moss-green glow at the mushroom's base. He hasn't moved in some time.