Extreme cold, firewood monopolized. Thermal engineer Solstice Shen transmigrates as an exiled illegitimate daughter into a deadly situation. She refuses to bow. She uses peat for briquettes, builds rocket stoves, heated beds, underfloor heating, turning 'waste' into black gold. She saves soldiers, warms barracks, fights hoarding. Solstice Shen's goal: not just survival—she wants chimneys to smoke in the Northlands, empower the poor, bring warmth, justice, hope.