Falling Skies

Dr. Michael Harris (guest star STEVEN WEBER -- Happy Town) joins the 2nd Mass with a theory about what might save the teenagers abducted by the aliens. But the plan could be derailed when Tom starts digging for answers to questions that have haunted him since the early days of the invasion. The 2nd Mass comes face-to-face with skitters and mechs when they attempt to rescue Ben.

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 (guest star BLAIR BROWN -- Fringe) who employed a suspicious means of surviving the invasion, making it unclear whether they can trust her. Anne and Lourdes make a shocking discovery about the skitters that could change everything for Ben. And Pope puts his expertise to use in trying to find a more efficient way to kill mechs by using their own strength against them.

Tom is still haunted by memories of his time with the aliens and begins to wonder if they did something to his mind. Pope, who is in charge of questioning Tom, plants seeds of doubt about him among the group. Meanwhile, Ben's hatred for skitters grows, and the 2nd Mass scouts locate an old bridge that will help them cross the river to safety ahead of an impending attack.

After the people of Charleston defeat another alien attack with the help of new advanced weaponry, Tom is invited to meet with powerful leader Benjamin Hathaway (guest star STEPHEN COLLINS). 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 a mission goes terribly awry, Tom and Pope must rely on each other to survive. Meanwhile, Weaver and company search desperately for two members of the 2nd Mass who have gone missing. And Marina (guest star GLORIA REUBEN) takes matters into her own hands in Charleston, disregarding Tom's authority.

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.