Life as We Knew It is the harrowing tale of a family trying to survive in a dystopian, post-apocalyptic world. A young adult novel, the story is told from the point-of-view of sixteen-year-old Miranda and takes the form of her journal entries. Miranda finds her world thrown into complete chaos when an asteroid hits the moon and shifts it out of orbit, moving it closer to Earth. Though the event is expected, scientific calculations about the event are somehow misread and dire consequences follow. The increase in the moon’s gravitational pull immediately causes massive tidal waves and tsunamis that decimate most of the world’s coastal cities. With the erosion of coastlines, even inland cities are soon destroyed. Power is disrupted, phone and cell lines work only sporadically and the nation’s supply lines are affected as well, leaving hundreds of thousands dead, presumed dead and/or missing.

Realizing that things will not return to normal anytime soon, people enter survival mode, including Miranda’s mother, Laura, who takes Miranda and her brother Jonny out of school to stockpile food and other basic necessities, in case things get worse. Along with their elderly neighbor, Mrs. Nesbitt, the group buys everything they can get their hands on at the supermarket. In a mad dash, with fights breaking out all around them, Miranda and her family are able to pack their van with canned foods, bottled water and toiletries. Miranda’s mother also makes the wise decision to stockpile winter clothes, batteries, oil lamps, and flats of vegetable plants. Though Miranda believes her mom is overreacting and initially takes a myopic view of the catastrophe, she helps out however she can. She becomes more optimistic about their chances of surviving when her older brother, Matt, manages to return home from college to be with the family.

When volcanoes begin erupting around the world, in places that have experienced this phenomenon before, things go from bad to worse. Dense clouds of ash block the sun’s rays, and the earth is thrown into a premature winter, further reducing the availability of crops and food supplies. Electricity is nonexistent, crops die and insect-borne diseases spread rapidly. Miranda’s friends either leave their Pennsylvania town, hoping to find a better life south or west, or begin to die of starvation. When snow comes early, the family is forced to drastically cut their food intake, trying to conserve their dwindling supply of canned foods until things get better. They also lose access to natural gas and water, adding to their troubles. A flu epidemic soon hits the town and decimates the remaining population. Miraculously, Miranda is the only one unaffected in her family. Demonstrating her newfound maturity, she skis to the local hospital in an attempt to find a doctor and family friend, Peter, to help her dying family.

Instead, the two nurses on duty tell Miranda that Peter, like most of the town, has died of the flu over the weekend. There is no medicine left, and there is nothing anyone can do to help Miranda’s family, as no one is strong enough to fight the flu. Miranda is determined to save her family, however, and over the course of the next few days, she nurses them back to health, even saving them from accidental smoke inhalation. Her mother and Jonny recover quickly, but Matt never regains all of his strength.

With their food supplies now practically nonexistent, Miranda comes up with a plan to buy her family more time. She tells her family she is going to ski into town to check for mail from their father. Matt, however, senses that she is really leaving the house so she can die without their mother having to see it. Miranda agrees to leave the skis nearby so Jonny can have them after she is gone. Most of the family’s energy has gone into ensuring that Jonny survives after they have all gone. Miranda manages to make it to town by foot, but finds the post office closed. Right before giving up all hope and giving into death, she finds, to her amazement, people in city hall giving out bags of food. Each family member is allowed one bag of food a week. As the program has been going on for some time, she is entitled to four bags of food. One of the men brings Miranda home, along with her four bags of food. Seeing that her family is alive and in need of help, he promises to bring more the following week. The family celebrates by eating a full meal that night, rejoicing that more is on the way. Three days later, Miranda turns 17. Having come this far, Miranda finally writes in her journal that she has figured out why she has been keeping a record of everything that has happened to her. She writes that she does so in order to remember life as it was and as it is now when things are better for her and her family.