American Fallout

Penny Brinkman, a lone wolf doomsday prepper, builds her fully stocked doomsday bunker in the middle of the desert, intent on a life of isolation without help or human connection in case of a catastrophe. Casper Crabb owns a gas station close to Penny's bunker, woefully unprepared with sparsely stocked shelves, and desires to retire to see the wonders of the world with a special lady he hasn't met yet.

Then, a global incident threatens to get the U.S. and Russia involved in a conflict that could lead to nuclear war. Penny goes to Casper In need of water, knowing he can get it to her the fastest. Casper is struck by Cupid's arrow. Penny can't afford Casper's prices, so he suggests she mentor him on prepping his station for a discount. She refuses, believing his intentions to be romantic. Then an incoming-missile alert that turns out to be a false alarm cuts off all communication and leads a panicked Penny to agree to be Casper's mentor.

Penny, all business, coaches Casper on how to prepare for nuclear war. She rejects the advances of the leader of a biker gang and connects with the abused daughter of a doctor, who is another lone-wolf survivalist. She insists Casper has an underground bunker to protect him from radiation. He asks if she would share her bunker and she refuses. As attraction leads to flirtation, Penny mock-kidnaps Casper to test his fortitude, then shows him how to survive in the desert. Around the campfire after a couple of beers, Penny reveals the personal reasons why she's so isolated, showing real vulnerability, and they have sex.

As the international incident starts to spiral leading to an ultimatum between the superpowers, Penny dismisses their night of passion as nothing. She is intent on bunkering down alone but still agrees to be Casper's mentor because of their agreement. He asks her to take one of his walkie-talkies and be part of his network, and she refuses. She makes enemies with the biker gang leader by letting him know she prefers Casper in a doomsday scenario and confronts the doctor about how he treats his daughter. Penny then finds she is taken to Casper as he shows he's becoming an adept prepper.

When Penny's water arrives, Casper gives her his last walkie, they have the best night of their lives together, and make love again. The next day Penny insists on Casper bunkering down with her. Then the U.S. and Russia call a truce bringing the world back from the brink. Casper asks Penny to join him in his retirement to see the world. She gets scared, insists on being by herself, and breaks things off. Then, after tensions were seeming to diminish, nuclear war occurs.

Penny, recognizing how emotionally unprepared she is, runs back to her bunker as Casper begs her to stay. Penny holds up in her bunker and Casper tries to get her out, leaving a walkie. As she waits out the aftermath, a mother and child get caught in her booby traps. No longer the paranoid lone wolf, she takes them in and ensures they survive, changing her perspective on the need to connect with others.

Numerous survivors from a nearby town come upon Casper's station. He provides for them in his newly prepped station. He calls the doctor to help the survivors, but the doctor shows up with a humvee full of armed goons and threatens to take his station. Seeing this, the biker gang approaches Penny to help Casper.

Penny arrives at Casper's station, armed, attempting to save him and the others. With the doctor taking both her and Casper hostage, Penny expresses her love for Casper and her desire to never be alone again. Casper then disarms the doctor, and with the help of the biker gang hiding in Penny's truck, runs the doctor and his goons off. With the doctor's daughter staying, Penny and Casper proclaim their love for each other and prepare themselves to survive the end of the world.