A plane crashes in the middle of the ocean and the four survivors, three men and a woman, wash up on a deserted island.
They set up camp and wait.
Weeks go by.
They're all getting pretty horny at this point so they come up with a plan that is fair to everyone:
The guys will take turns and each will get the girl every third night.
Months go by and everything is working out well.
The guys are getting enough to keep them happy and the woman is happy to be getting drilled every night.
Then, one day, the three men wake up to find the woman dead!
A month goes by and things are pretty normal.
Another month goes by and things are starting to get a little sketchy.
A third month goes by and things are getting out of hand.
A fourth month goes by and things are downright disgusting.
The fifth month goes by and they bury her