Nightmare Mountain — Peg Kehret

As soon as Molly arrives at her aunt and uncle's ranch in rural Washington, things start to go very wrong. Her cousin hates her on sight. Her aunt falls into a mysterious coma. Then, left alone on the huge property, Molly and her cousin discover an intruder lurking in the barn! Armed and desperate, he drags them to the top of a nearby mountain--and triggers an avalanche with a gunshot. Can they make it down the mountain alive?