S1, E8: 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.