There was someone in the house. Home alone with her young children during a blizzard, a mother tucks her son back into bed in the middle of the night. Then she hears a noise – old houses are always making some kind of noise. But this sound is disturbingly familiar: it’s the tread of footsteps, unusually heavy and slow, coming up the stairs… In that split second, she has three choices. Should she hide? Should she run? Or should she fight Tracy Sierra was born and raised in the Colorado mountains. She currently lives in New England in an antique…