While many preppers believe defense is the best strategy for surviving a Doomsday scenario, one family in Tacoma, Wash., is banking on a good offense. Tyler, his wife and his cousin have assembled a group of like-minded, would-be marauders from their neighborhood in preparation for a catastrophic domestic terrorist attack. They have only six months' worth of food because they plan on taking what they need in order to survive — and to stay safe, they're developing the ultimate suit of armor.

A devastating EF-5 tornado, like the one that struck Oklahoma in May of this year, can throw buildings into the air and hurt hundreds of people. In Tennessee, Tracy is preparing for just that. Tracy has spent six years prepping his farm for a super tornado, but if it does hit, he doesn't plan on hunkering down — he plans on gathering his family and making a getaway in his mobile safe room.

Meet two families who both fear the end of the world is fast approaching. In Texas, John Tucker and his family are preparing for Category 5 hurricanes that they believe will change the landscape forever. After living in a home that was split in two during a hurricane, John vowed he would never again be unprepared. And in Utah, brothers Bret and Shane are preparing for a complete economic collapse. To protect their families, they are building a sniper post complete with the ultimate sniper rifle.

Meet two Tennessee families who are both preparing for an earthquake in the New Madrid Seismic Zone. David Mays believes all roads and bridges leading out of his neighborhood will be destroyed, so he's devising the ultimate Doomsday drone fleet. Meanwhile, 100 miles away, do-it-yourselfer David Nash is building a geodesic dome -- considered one of the most stable structures on earth as it eliminates the need for load-bearing walls -- that will house his family during the earthquake's aftermath.

n Georgia, Mark believes that the U.S. is under the threat of foreign occupation, specifically by Russia. He's building a modern Trojan horse in order to infiltrate a potential enemy base undetected. In Texas, Joe is preparing for a cyberattack to take out the country's telecommunications system. His current projects include a post-apocalyptic schoolhouse to be used to educate children if the government collapses after disaster and "gyro-copter" in order to maintain aerial dominance.

Some preppers believe in safety in numbers -- as is the case for Jeff Mann, who leads "the Colony," a community of 25 preppers unified with the single purpose of surviving doomsday. Watch as he prepares his son, Colten, to take the reins by having him hunt down live boar in the Florida swamps and builds the Colony's very own gallows -- an important message that there are laws to be upheld, even in times of chaos.

An economic collapse could mean total chaos for the U.S. -- looting, riots and civil unrest are top concerns. In Washington state, Steve works with a stern hand to prep his family for the potential threat. South Carolinian David Appleton is a comedian, but the idea of a devastating earthquake is no joke to him. His job doesn't always pay the bills, so David must Dumpster dive to find supplies to make a DIY camouflage net to hide his preps.

To protect his family from Doomsday marauders, Rob is devising the ultimate booby-trap system. He's securing his Texas property's perimeter with an elaborate system of alarms, traps and defense mechanisms. In Tenn., Greg is preparing for a financial catastrophe by building an invisible tree house where he hopes to be safe from looters. If the build goes as planned, his family will have a tree house 12 feet into the forest canopy, with mirrored paneling and a stockpile of food, water and ammo.

The possibility of World War III is a major concern for many preppers, including former Marine Alex Dunbar, who is training a private army of German Shepherd attack dogs in San Luis, Colorado. In the woods of East Appalachia, Brenda McSwigan fears that a vicious mutating virus will lead to a pandemic that will overwhelm hospitals and leave the rest of the country in chaos. Another prepper, Grace McLeod, secures her 3,500 square-foot fortress before an economic collapse.

Could an explosion on the surface of the sun cause mayhem on Earth? Jason and Jacob are a father-son team from Alabama who are prepping for exactly that: a global solar flare with the potential to wipe out power grids around the world. Jason was almost stranded for good in the wilderness when he was 19, but that will not stop him from prepping in those very same woods by molding his own ammunition and preparing his 20-piece bug-out pack.

In Texas, Kenny and his wife Connie are preparing for a civil war. With defense as their ultimate concern, they're building a fortified bulletproof rooftop command center. In Maryland, Kevin is prepping for an EMP attack. Kevin is very protective of his close-knit family, including his three pregnant daughters. Their survival plan relies on a customized 15-ton bunker buried 20 feet underground and stocked with baby supplies and doomsday essentials

Prepper Chad believes that a nuclear strike resulting in a genocidal siege is a real possibility. At his home in Arizona, he is working on executing the biggest prep of his life — a 140-foot-long escape tunnel from his family's house to a bug-out vehicle. With the help of his wife and daughter, he begins construction — but as the project unfolds, they realize they're in over their heads.

Outside of Fort Worth, Texas, Vietnam veteran Richard Huggins is preparing for a nuclear strike by a terrorist state, a concern he believes is amplified by his proximity to the defense production hub of Dallas-Fort Worth. Meanwhile, in rural Colorado, Dr. Dave, his wife, Dee, and their young daughter are prepping for a possible solar flare that could lead to widespread illness and death due to lack of medical care.

Deep in Oregon's backcountry sits an 80-acre off-the-grid estate that prepper Curt and his family have designed as a fortress in the event of an economic collapse. Isolation is one of their greatest strengths, but the protective measures are endless: a 3,000-square-foot greenhouse, a lake with 1 million gallons of water, infrared cameras and a high-tech software system — not to mention the children are trained in marksmanship.