Summary:The world is left in tatters after a sudden, unprovoked and unexplained invasion by aliens, leaving the planet’s remaining human population to fight for survival against the occupiers. History professor Tom Mason has been named second in command for the 2nd Mass, but his real focus is on his three sons, one of whom has been captured by the aliens for an unknown purpose. While scouting for supplies, Tom, Hal and their squad encounter a gang of marauders determined to get their hands on the 2nd Massachusetts’ weapons. Leading the gang is an ex-con named John Pope, who decides to use his hostages as bargaining material.

Summary:Tom is assigned the task of searching an abandoned armory for possible weapons. During the search, his team is attacked and captured by a gang whose leader ransoms them for the 2nd Mass cache of weapons.

Summary:Tom and Hal lead a squad in a search for supplies but are ambushed by a rogue gang of humans led by ex-con John Pope, Pope plans to use the hostages to gain control of the 2nd Mass’ supply of weapons that they’ve stockpiled since the invasion began.

Summary:Tom and his team head out to track down more motorcycles for the 2nd Mass., relying on Pope to guide them to a good location. They hit the jackpot until they meet some skitters and harnessed teenagers at the bike shop. Back at the base, Dr. Harris and Anne disagree over the best method to gather more intelligence on the aliens.

Summary:Hal comes up with a risky and dangerous plan to infiltrate a skitter’s lair and rescue Ben and other harnesses kids that are being held captive.

Summary:Another resistance militia leader, Clayton, arrives in camp warning of a coming alien assault, and with time running out, Tom and the camp must weigh his offer to take their children to a safe haven.

Summary:Hal begins to suspect the farm is not the idyllic safe haven Clayton said it was, and when Mike stumbles upon the horrifying truth, he and Hal find themselves up against an unforeseen enemy.

Summary:Weaver turns more and more erratic, stirring up trouble while on a reconnaissance mission with Tom and Hal. Meanwhile, Pope constructs a potent weapon; and Anne makes a startling discovery while performing an autopsy on a skitter cadaver.

Summary:Growing tension divides the 2nd Massachusetts just as their ambitious assault on an alien base draws near. Meanwhile, Tom has trouble coming to grips with Annie's profound discovery and its implications.

Summary:In the season finale, the resistance fighters launch a bold attack against the aliens as Tom remains at the camp to protect the civilians. Twisting developments lead Tom to a close encounter of the harrowing kind, and mysteries about the aliens' motives might finally be answered.