I had never even heard of Dead Within, only finding out about it after it got a mention in the comments on this Final Girl post. But it was streaming on Netflix and short - a taut 91 minutes - just perfect to watch before bed.
In Dead Within, you really should settle down and watch the opening credits. There are two couples, one with a baby and a super-cute yellow lab, out for the weekend in a rustic cabin somewhere. There is making of dinner and drinking of wine and laughter and smiles and it all looks like the start of a really nice weekend away among friends. Then the credits end and we cut to black. When the movie starts back up, it is six months later. One of the couples, Kim and Mike, are still in that cabin but they've boarded up all the windows and barricaded the doors and they skulk around almost silently, clutching machetes and shotguns, flinching away from the horrible shrieks and growls that come from outside the cabin. They are alone in there: their baby is gone, their dog is gone, the other couple is gone. It seems the world outside has gotten hit by some sort of rage zombie apocalypse (kind of like 28 Days/Weeks Later, I guess); the virus isn't in the water but it is very contagious. You can tell the infected (the "trollers" Kim and Mike call them when they are heard outside the cabin) by their black eyes, black blood and general shrieking murderousness. Mike goes out every few days, armed with the shotgun, to scavenge what he can - canned goods, batteries, soap. But Kim stays in the cabin, and the movie stays with her, and it is there that she starts to go mad, terrified of what may be outside. She has no idea what's out there - Mike won't let her go out and there are only partial glimpses through the boarded-up windows - and she can't tell if it's scarier within the cabin or without.
I thought this was a solid little low-budget horror flick. It's a just little gory but the main terror comes from the claustrophobia of being trapped in the tiny cabin with Kim. We only get her point of view. She tries so hard to be brave but the noises from outside are so scary, and sometimes not knowing is worse than knowing. To the movie's credit, it keeps the viewers in the dark right up until the end: we never get a clear view of the world, never know if it's real or all in her head, and that keeps the unease and dread going. My only complaint was that the sound levels were uneven: the music was loud but the dialogue was soft and I found myself having to adjust the volume a lot, and missed out on some dialogue even so. Still, I can definitely recommend Dead Within - go watch it!
53 minutes ago