When an alien race wipes out the majority of the human population, a group of survivors gather to fight back against a highly intelligent, heavily armed alien force whose purpose on Earth is the biggest mystery of all.

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

The 2nd Mass come face to face with Skitters & Mechs when Tom & Hal lead a mission to rescue Ben and the others. Tom's search for answers to nagging questions could jeopardise the plan presented by Dr. Michael Harris.

Tom and Hal lead a team to find more motorcycles for the 2nd Mass after Pope provides details on where they can be found. Back at base, Dr. Harris and Anne disagree over the best tactic to gather more intelligence.

Hal devises a new plan to save the captured teens but pulling it off could put someone in danger. Following a sudden tragedy, Anne makes a discovery that could mean the difference between the plan's success or failure.

Lt. Terry Clayton of the 7th Mass arrives at 2nd Mass HQ to warn of an impending alien attack. Clayton claims to have a plan to lead the children to safety but his plan is met with strong resistance by the parents.

Hal finds himself having to take control and fight when an unexpected threat presents itself. Anne faces her own problems when Sarah goes into labour as 2nd Mass is being evacuated in anticipation of the alien attack.

Weaver's mental state continues to deteriorate causing trouble for Tom and Hal on a reconnaissance. Pope builds a potent weapon to use against the aliens & Anne makes a shocking discovery performing a Skitter autopsy.

As the assault on the alien base draws closer, tension builds amongst the members of the 2nd Mass. Tom struggles to come to terms with Anne's new discovery about the Skitters.

Tom stays behind to protect the camp and its occupants while the rest of the resistance launch an attack on the alien base. Information regarding the aliens' motives finally comes to light.