Besides gathering basic human necessities, like clean water and food, the 2nd Mass needs to collect weapons to defend themselves against the invading alien forces. Their best bet is to hit a fully stocked armory. The question is -- could the abandoned building be a trap? There's only one way to find out.
The first to move in are Dai and Tom. After spotting old mech tracks surrounding the armory, they decide to go a little further and test the security. The men, along with Hal, Anthony, Click, Karen and Jimmy, decide to use a golden retriever, named Nemo, as bait. Nemo chases a tennis ball they throw right into the center of what could be a trap, and unsurprisingly, a towering mech lumbers out from nowhere with its lasers set on the four-legged soldier. Jimmy, a fighter barely in his teens, can't bear the possibility of losing Nemo and spontaneously runs out to save the dog. The Mech spots Jimmy, but before it can shoot or harness him, the rest of the group has enough firepower and time to rescue Jimmy, Nemo and themselves from the alien.
The next morning, Tom awakens his youngest son, Matt, as he sleeps in "his" bedroom -- part of an abandoned house in an area the 2nd Mass is temporarily squatting in. Tom reports to Weaver about the previous night's mission, including Jimmy's mistake. No-nonsense Weaver orders Tom and his men to return to the armory tonight and complete the mission they failed the night before; however, Tom reminds his supervising leader that tonight he was promised the opportunity to search for his middle son, Ben, believed to be one of the harnessed children. Before Tom has a chance to argue any further, Anne interrupts their discussion.
She asks Weaver why it is that only fighters get to sleep in the cushy homes, while most of the civilians are left, literally, out in the cold. She defends these people, demanding that Weaver and the other soldiers offer them respect and a little kindness. However, her request seems to fall on deaf ears. Anne asks a hungry Tom what he thinks about the discussion of soldier vs. civilian and his stance lies somewhere between both groups.
The civilians have settled within a meadow valley, where they work together to gather water, prepare food, do laundry and try to maintain a sense of normalcy. Anne's uncle, Scott, has fallen into the role of educator for the school-age children, including Matt. He teaches a lesson about biology and how skitters are now a part of life on Earth and a subject that humans can now study.
After "school" ends, Scott and Tom share their thoughts about the extraterrestrial invaders. Scott says that the skitters must come from a planet similar to ours, but he mentions an interesting observation: We humans have created robots, for the most part, in our likeness (two legs, one core); however, skitters have six legs, while their robots, Mechs, are bipedals. In other words, their robotic counterparts don't seem to look like themselves. Tom considers this and suggests that perhaps the purpose is to have a greater psychological impact on humans.
Mike, a fellow fighter in the 2nd Mass, approaches Hal to ask about the harnessed kids he saw earlier. Mike was hoping that Hal may have spotted his missing son in the same group as Ben. Unfortunately, Hal isn't sure if Mike's son was among the harnessed children, but he invites the worried father to join the rescue mission he and Tom plan to make later.
Lourdes runs into Hal and Karen and offers to help them carry some heavy supplies; however, it's obvious (at least to Karen) that Lourdes actually just wants to get closer to Hal, her crush. She mentions that she hasn't lost faith, even in a time of total despair, and still continues to pray to God. Karen isn't impressed with Lourdes's piety and stalks off.
She and Hal continue their walk, eventually ending up in a bedroom in one of the houses the 2nd Mass is squatting in. They contemplate what the former resident was like and if she's still alive, then Karen starts teasing Hal about his effect on the ladies (specifically, Lourdes). The former lacrosse player responds that he only has eyes for one girl: Karen. The romantic moment is interrupted when Tom enters the bedroom, informing Hal that instead of rescuing Ben tonight, they've been ordered to return to the armory.
That night, Tom's group preps for the mission; however, Jimmy is told to sit this one out. He's a good soldier but his mistake from the previous night, when he let his attachment to Nemo cloud his judgment, makes him a liability for the others.
The team enters the building, when all of a sudden, an arrow fatally hits one of the members square in the torso. He instinctively fires his gun in response and ends up hitting an armed man, meaning that this attack was initiated by humans, not aliens. A voice rings out demanding Tom and his men drop their weapons, or else Hal and Karen will be shot next.
Tom's team is captured by a band of outlaws and brought to what looks like an abandoned theater. One of the bandits, named Billy, has been shot through the leg and needs medical attention immediately. However, the gang's leader is more interested in his new "guests." He questions them about their identities, but Tom lies, saying that they're just a bunch of strangers who came together in Cambridge. The gang leader doesn't buy it.
He says that he's going to make Hal and Karen part of his gang, and the other fighters will be killed, including Tom. Hal scrambles to keep his father alive and the truth comes out -- they're members of the 2nd Massachusetts, an army of resistance fighters. However, the truth doesn't surprise the gang as they seem to already know about the 2nd Mass. It turns out, they've been watching the resistance members for two days. The gang leader, John Pope, even knows that Tom and Hal are father and son.
The leader says he'll trade Tom's team for Weaver's .50 caliber machine gun and functioning car. Hal, escorted by one of the outlaws, Margaret (also known as Maggie), will be the one to deliver the demand.
After Hal leaves and the rest of the kidnapped group is moved out of the auditorium, Tom and John Pope, his captor, have a heart to heart. Tom tells him that he used to teach American history, before the invasion, and that he believes in the 2nd Mass and what they're trying to accomplish. Pope balks at this comment but admits he's having a blast since the invasion began. He loves killing the "cooties" (otherwise known as skitters), and offers some advice about the best way to take the aliens out. To prove his point, he shows off the corpse of one of the Cooties/Skitters he killed. Pope shares his knowledge about the creatures and their ships, saying they respond to sound and heat, respectively. He and his guys even tried to take down a ship with a bazooka, but were unsuccessful.
Meanwhile, Maggie escorts a blindfolded Hal out of the gang's lair and tells him he has one hour to broker a deal -- the safety of his father and friends in exchange for the machine gun and car. He meets up with the 2nd Mass and informs Weaver and Anne what's going on.
As Tom awaits word from his group, he shares a beer with Pope. The outlaw suggests Tom put his son, Ben, out of his misery so he doesn't have to live like a harnessed zombie. He also divulges that he has (or more likely had) kids living in Florida. He notices Tom trying to eye a way out and tells him to forget it. Though the mood is slightly tenser now, Tom offers Pope a spot in the resistance, since the outlaw seems to know how to kill skitters. Pope laughs at this suggestion, since he believes the resistance effort is a joke.
Weaver doesn't want to negotiate with the gang. His first concern is the civilians so he decides to move everybody out quickly and quietly. Obviously, Hal has a problem with this plan since it doesn't involve rescuing his father and his friends. Weaver orders Mike to guard Hal so he doesn't do anything stupid, but instead, he lets the young fighter go in order to save Tom.
Anne accompanies Hal back to the spot where Maggie left him, saying that she can help save Billy, the wounded member of the outlaw pack and Pope's brother. Anne stops his bleeding, while Pope now decides to rob the 2nd Mass since Weaver wouldn't do a swap.
Pope arrives to steal from Weaver's supplies. He demands the .50 caliber machine gun, the GTO and food, or he'll start firing on the civilians. And because he launched a flare in their vicinity, it's only a matter of time before it attracts the alien ships and they open fire. Weaver is forced to concede.
Back in the auditorium, Billy orders a frightened Karen to stand up so he can check her out. His remarks about her appearance have an ominous tone. This seems to trigger something in Maggie, so she asks Anne if Billy will survive. When Anne says yes, Maggie succinctly shoots Billy along with the other gang member. Maggie tells them that the outlaws grabbed her three months ago and in not so many words, they'd been assaulting her ever since.
Tom and his team return to the campsite, to save the civilians and take on Pope and his remaining gang. The outlaws are outmatched and end up stuck in the middle of the flares, a precarious spot when the airstrikes begin. Tom offers Pope two choices: join the resistance or die. Though he resists at first, the gang leader is eventually captured.
The 2nd Mass relocates to a local high school, and Weaver has a lot to say about what went down in the last 24 hours. He's angry that Tom almost lost his squad, that a bunch of criminals almost stole their food, that their only doctor almost died -- he wants the chain of command to be followed. However, he does allow Tom three days to try and find the harnessed kids, including Ben. In the meantime, Tom is responsible for the squad's prisoner, John Pope. The former outlaw learns that Maggie is earning her citizenship in the 2nd Mass by becoming a fighter.
Tom gets a few precious minutes to reconnect with his youngest son, Matt, and play a simple game of catch. The sweet moment between the two is cut short when the team departs to rescue Ben and the other harnessed kids. The future may be uncertain, but the 2nd Mass won't give up without a fight.