Molly and JD discover another pregnant woman suffering from inexplicable and fatal symptoms, while Molly begins to question her own mental stability. Meanwhile, Julie struggles with Ethan's rebellion.

Molly finally learns the frightening truth about what happened to her son. Also, Julie's decision to erase Ethan's memory has disturbing conveniences.

As Molly continues to experience blackouts, she is helping the government crack the DNA code of the spores.

Molly discovers Ethan is alive and sets out to get her son back. Also, suspicions about John's death cause JD to investigate Julie's potential involvement.

Molly has become convinced the Aliens are on Earth for peaceful reasons. She and J.D. reach out to Toby for peaceful negotiations with the aliens.

The second hour of a two-hour episode, Molly tries to reconcile whether she wants to be loyal to the aliens or remain loyal to the humans. JD becomes skeptical of the aliens after one gives him a flashback to his days in combat.

Following a near-death experience, Molly has a harrowing vision she can't shake. Also, Shepherd's loyalty to the Global Space Commission is called into question.

Molly manages to find John's former colleague with JD and Ethan hoping to be able to stop the Humanich threat. Julie sends Charlie on a mission to discover where Lucy's orders are coming from.

Molly reveals disturbing new details about Shepherd's death to the GSC, and Lucy makes a powerful move against the humans and hybrids that could have devastating global repercussions.

Molly and JD frantically race to the hybrids to stop a Humanich plot that will destroy the human race. Also, Lucy has a shocking realization about the GSC that forces her to question her allegiance and put Ethan at risk.