Lynne Deragon

In the first part of the two-hour series premiere, the world is left in tatters after a sudden, unprovoked and unexplained invasion by aliens, leaving the planet's remaining human population to fight for survival against the occupiers. History professor Tom Mason (Wyle) has been named second in command for the 2nd Mass, but his real focus is on his three sons, one of whom has been captured by the aliens for an unknown purpose.

Hal comes up with a dangerous new plan to rescue the captured teenagers from the aliens, but it might require putting someone at risk. Meanwhile, a sudden tragedy causes Anne to make an enormous discovery that proves instrumental to Hal's risky plan.

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.

A couple kidnaps their baby from its adoptive parents and steals their car to flee the scene after changing their minds about giving the child up.