Ben is endangered by someone who he thought he could trust. Tom captures another hostage. Weaver offers Matt a job to lift his spirits. The 2nd Mass are trapped in a basement and face a new enemy.

When skitters approach the newly combined resistance force, the groups’ interaction surprises everyone. Meanwhile, Tom finds out life-changing news just as the 2nd Mass comes face-to-face with their most dangerous threat to date.

With Weaver leading several squads of fighters against the aliens, Tom remains behind to help protect the civilians as they evacuate. But a major breach in security endangers both the soldiers and the civilians. Tom is confronted with a decision that may lead him to discovering what the aliens want with the captured teenagers, humankind and the planet.

Hal stumbles across bodies of de-harnessed kids and finds someone from his past. Tom and Anne grow closer. And Weaver’s health deteriorates just as Tom discovers he may have been keeping important matters from the group in order to protect them.

The 2nd Mass moves into an airport hanger. The Berserkers plan to get rid of Tom. While dealing with a loss of one of its own, the 2nd Mass receives a promise of hope from a mysterious visitor.

With hostilities escalating between the resistance and the alien invaders, Tom calls on a nuclear specialist known as "The Rat King" to come up with a plan that will strip the aliens of their power. As suspicion continues to mount about a mole within the resistance, Tom and his leaders make a drastic decision that jeopardizes trust among the group. Anne, meanwhile, has a feeling that all is not right with her newborn.

While members of the 2nd Mass attempt to dig out a shot-down Beamer, Tom and a small team follow the Volm to a supply cache in search of equipment to expedite the process. Along the way, they encounter a friend, and must decide whether or not to trust her. Back at camp, Maggie and Ben grow closer as he teaches her to hone her new skills, while Pope and Sara continue to clash, resulting in a fight from which they may never recover.

With the weight of humanity’s survival on Tom and Lexi’s shoulders, they must defeat Tom’s mortal enemy and find a way to destroy the omnipotent Espheni Power Core. Meanwhile, a new, terrifying Espheni Bomb is dropped onto Chinatown, immobilizing the 2nd Mass and preparing them for Human Skitterizaton.

Season three of Falling Skies opens seven months after the 2nd Mass arrived in Charleston. In the interim, Tom has been elected to political office, but he has his hands full as the resistance continues to battle the alien invaders. Tom’s decision to have the rebel skitters fight alongside humans creates tension and raises suspicions that someone may be feeding secrets to the enemy. Meanwhile, Hal struggles with nightmares that seem so real, he has difficulty knowing if he’s awake or dreaming. And Tom and Anne prepare to welcome their baby.

After the people of Charleston defeat another alien attack with the help of new advanced weaponry, Tom is invited to meet with a powerful leader. While Hal wrestles with an invasive evil, Ben struggles with his identity and the notion of being human again. And Anne uncovers startling new information that puts everyone in jeopardy.

When the 2nd Mass destroys a crucial Espheni base, a relentless enemy is taken down and the Mason family is reunited with those who had been lost. But the arrival of more interstellar players puts the fate of the Earth’s remaining survivors in doubt.

After breaking out of the Espheni Ghetto, Tom and the 2nd Mass seek refuge in a Volm hideout, where tensions run high between the Volm and humans. Tom sets off with Weaver and Cochise to find Matt, leaving Hal in charge. Meanwhile in Chinatown, Anne is reunited with Lexi, and comes to realize that the little girl she saw 6 months ago is now a grown woman.

Tom gains a powerful new weapon. Ben puts his life on the line to extract enemy plans. Pope discovers that Tom is alive. Meanwhile, the 2nd Mass must reassess their situation when an unexpected visitor appears.

The 2nd Mass meets new faces, while Tom comes across his former mentor, but it’s difficult to know whom to trust. Maggie realizes that Pope may not be sticking with the group very long. Tector embraces his military past.

Tom uncovers confidential intelligence about the heart of the alien operation. Meanwhile, Charleston prepares to mount an offensive against the Espheni, but a massive explosion brings the operation to a halt. And the identity of the mole is finally uncovered, but not before more blood has been shed.

Tom and the 2nd Mass hatch an elaborate plan to escape the confines of the Espheni Ghetto. Meanwhile back in Chinatown, after learning from Ben that Lexi has been keeping a deadly secret, Maggie confronts Lexi publicly. At the Espheni Youth Camp, Matt tries to talk Mira out of a dangerous escape plan. While trekking through the woods with her guerilla fighters, Anne has a flashback to her time in the Espheni Tower with Karen, where a terrifying secret about Lexi is revealed.

Tom’s mission to destroy the Espheni Power Core is complicated by Lexi’s return. Lexi is forced to take extreme measures to save her father’s life – and her own – after a Beamer malfunction. Meanwhile, the 2nd Mass fears an impending Espheni strike by the scorched Overlord.

A surprise skitter attack leaves the 2nd Mass without food. In desperation, Maggie, Ben, Pope, and Sara go on a dangerous mission hoping to find supplies.

The 2nd Mass discovers the source for the seemingly endless supply of enemy forces. Hal disobeys his father.

The 2nd Mass arrives at a safe haven. As the two groups make plans for the final assault on the Espheni, the 2nd Mass begins to realize that things aren't exactly as they seem.

Weaver discovers a shocking truth about an old friend and must decide how to best protect the 2nd Mass. Maggie and Isabella are forced to work together.

The 2nd Mass prepares to take the fight to the invaders with an assault on one of their bases. But Weaver’s increasingly strange behavior worries Tom that he might not be fit to command. Hal and Tom encounter a left-behind woman who employed a suspicious means of surviving the invasion, making it unclear whether they can trust her.

Weaver is still in command of the 2nd Mass, while Anne continues to serve as medic. They have seen many battles and are a much leaner unit now. Pope has taken command of the Berserkers, a renegade group within the 2nd Mass that Weaver doesn’t fully trust.

Tom is haunted by memories of his time with the aliens. Pope plants seeds of doubt about him among the group. Ben’s hatred for skitters grows. The 2nd Mass locate a bridge that will help them cross the river to safety ahead of an impending attack.

The two-year anniversary of the alien invasion is fast approaching as the people of Charleston prepare for another potentially devastating offensive. A sniper attack by an unlikely gunman creates questions and doubts within the new government. Hal believes he knows the identity of the mole. And Anne’s concern for her baby continues to grow.