The story begins six months after a devastating alien invasion has decimated most of the human population and crippled Earth’s infrastructure. The aliens, known as the Espheni, have deployed a variety of advanced technologies and monstrous creatures to subdue and control humanity. The series focuses on a group of survivors in Massachusetts who form a resistance group called the 2nd Massachusetts Militia Regiment, or the 2nd Mass.

The central character is Tom Mason, a former history professor turned militia leader, played by Noah Wyle. Tom’s knowledge of military history and tactics becomes invaluable in their fight against the alien occupiers. His primary motivation is the safety and survival of his three sons, one of whom has been captured and harnessed by the aliens. Throughout the series, Tom evolves from a determined but relatively inexperienced leader into a seasoned and strategic commander.

The show also features strong supporting characters, including Anne Glass, a pediatrician and Tom’s love interest; Captain Weaver, the gruff and experienced military leader of the 2nd Mass; and John Pope, a renegade outlaw who becomes an uneasy ally to the resistance. Each character brings their own strengths and perspectives to the fight against the aliens, creating a dynamic and often tense group dynamic.