ll in all a traditional summer comedy, except for the fact that it's the end of the world. It's Midsummer Eve, and the sun blazes from a cloudless sky. At the camping ground, vacation season has started. Buses arrive to transport the guests to the great Midsummer party some distance from the camping ground. However, two couples decide to stay behind and enjoy the tranquility and they decide to celebrate Midsummer Eve together. They have not celebrated long before extraordinary natural phenomena surround them. With Mrs. Sørensen's arrival, the peculiar natural phenomena escalate. But the cabin guests continue partying. As nature steps up its attack, and things actually start resembling Doomsday, they discover that little Simon is missing.

Overview from themoviedb.org