One day, electricity just stopped working and the world was suddenly thrust back into the dark ages. Now, 15 years later, a young woman's life is dramatically changed when a local militia arrives and kills her father, who mysteriously—and unbeknownst to her—had something to do with the blackout. An unlikely group sets out off on a daring journey to find answers about the past in the hopes of reclaiming the future.
Handlingen kretsar kring invånarna i Jericho, en fiktiv liten stad i Kansas (USA), kring följderna efter flera kärnvapenexplosioner runt om i USA. Serien börjar med en synlig kärnvapenexplosion i okänt område nära Denver, Colorado, vilket resulterar i att all el försvinner. Senare återkommer dock elen till Jericho, men snart förstör en elektromagnetisk puls (EMP) all elektronik.
A group of teenagers wake up to a world where the adults have mysteriously disappeared and all technology has ceased to function.