In '40 Days and Nights,' a catastrophic storm hits the world, causing mass destruction and forcing people to find a way to survive. A group of scientists and experts must come together to try and stop the disaster as they face various challenges and obstacles. As the storm grows more intense, the fate of humanity hangs in the balance.

A group of aliens arrive on Earth as part of an advance invasion force. Their mission is to kidnap a small sample of humans and run them through a series of rigorous tests to determine if they would make suitable slaves. Harper, one of the alien experimenters, has become frustrated with her planet's endless cycle of conquest and extermination and begins to feel some sympathy for her human captives. While the prisoners see a glimmer of hope in the compassionate alien, will it be any use in stopping the enormous attack fleet just a few days from Earth?

Lieutenant John Barton is sent on a special mission to deliver a special vaccine to a distant mining colony. He is infuriated to find Lee, a stowaway aboard his spacecraft. Barton has only enough fuel to carry himself and his precious cargo, and Lee's added weight insures that they will crash if she stays on board. They have gone too far to turn back, and Barton's superiors make it clear: the mission takes precedence and Lee has to be dumped into space. But she won't go quietly.