This was good! And a Question
SPOILER:
Anyone else watch this and kept thinking the crazy looking uncle locked them in the sauna on purpose? Right to the end, I thought it was the uncle that was responsible.
There were lots of "clues" to make us think along those lines: the sound of a struggle outside the door just before they get locked in; the odd disappearance of Michael; Wade's moonshine (drugged?); Wade and his buddy busy in the woods; Wade's mean looking dog; the point of view shots from the thermostat, suggesting someone watching via a camera...
Also, somewhere about the halfway point, just after they break the little window, as the camera pulls back from outside the sauna door you see a glimpse of what looks like a head watching from the bottom right of the frame.
Trouble is, if you get people worked up into thinking it's going to be a slasher movie, they're likely to be disappointed when they find it's not.