The Cabin in the Woods follows five college buddies--Dana Jules, Holden, Marty and Curt, as they set off on a weekend getaway to an isolated cabin set in the woods. As watch Knock at the Cabin online begin to explore their surroundings, they quickly discover that they are not alone and that their vacation has taken a sinister turn.
The group soon realizes they are pawns in a much larger game when they are confronted with various horrors, that are both human-made and supernatural. As the night progresses, the five friends must survive the night or risk death.
The group initially breaks up in two parts: Dana and Marty remain inside the cabin, while Jules, Holden, and Curt examine the mysterious events happening outside. After a couple of close calls, Dana and Marty return to the cabin with news that the creatures outside have been killed and then discover they have no idea that Jules, Holden, and Curt have not returned.
The other two go out in search of their friends. In the process, Dana realizes the monsters are scientists of a government agency who have been mutated into monsters and taken to the cabin for an experiment that is secretly conducted.
They eventually find and save their companions, and they manage to escape the cabin and return to their vehicle. Despite their best efforts the group is not able to defeat the mutant creatures, and they must seek refuge in a mine shaft that is abandoned.
In inside the mining facility, they stumble upon a control room and find out the real purpose behind the secret experiment: to create a new type of monster that could be used fight in a war. After a brief struggle they can shut down the experiment and escape the mine alive.
In the final analysis, all five of the college buddies survive the ordeal, although they're all deeply shocked by their experiences. Despite the horrible experiences they endured however, they're determined to put this incident behind them and go back to normal life.