晴朗的一天，三年前痛失男友的珍娜（丝柯·泰勒-考普顿 Scout Taylor-Compton 饰）与好友瑞妮（克里斯蒂娜·尤罗尔 Christina Ulloa 饰）、迈克（迈克尔·科彭 Michael Copon 饰）以及新结识的帅气青年伊安（特拉维斯·范·文克 Travis Van Winkle 饰）前往某个乡村，参加当地举行的五月节。湖畔小屋，笑语欢歌，青年男女们纵情欢乐，只有珍娜强颜欢笑，似乎久久无法从三年前的惨剧中走出。随着夜幕降临，四人走入桑拿室，体会无上的蒸汽享受，而危机也正一步步向他们迫近。在此期间，迈克和瑞妮突然爆发争吵，前者夺门而出，大发雷霆，而瑞妮和珍娜、伊安稍后却发现，他们三人却被意外锁在桑拿室中。 　　温度逐渐升高，而死神的脚步越来越近……Jenna, Renee, Ian and Michael arrive at a lakeside cabin owned by Ian's uncle Wade. Intending to enjoy a carefree weekend, instead, three of them become locked in the hot sauna. First they think its Michael playing jokes on them, but soon realize that help is not coming and they must find a way out before the heat kills them. As the heat rises they are pushed to their physical and psychological limits - staying alive is not easy any more. Breaking a small window - may be the worst thing they can do, because cool air will trick the thermostat to run the heater full blast. They need to get out, but all they can is wait! Wait for what, wait for who?! How long could you wait in the heat up to 250 degree Fahrenheit.