It began with a smell — faint, sour, and fleeting — drifting through the hallway like a whisper. At first, Tom Fisher, a 42-year-old homeowner in the suburbs, didn’t think much of it. He assumed it was something simple: a forgotten onion, old food in the trash, or maybe a spill behind the stove. He scrubbed the kitchen spotless, aired out the house, and went to bed thinking he’d solved it.
By morning, the smell was back.
