Six months after her life unraveled and dark secrets were revealed, Molly is confined to a psychiatric hospital when she learns of bizarre deaths that sound eerily similar to those she witnessed in space. When she escapes to investigate, she crosses paths with JD Richter, a determined cop who just signed on to the case.

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

为摧毁Ahdu，军方决定用无人机直接轰炸充满人群的酒吧，但是Molly和Ahdu在轰炸之前已经离开，Molly和Richter被捕，Ahdu逃脱。

As Molly works to create a virus that will eradicate alien hybrids, she discovers that aliens are trying to communicate with humans through a hidden message in their DNA. Also, Lucy helps Ethan run away from Charlie in order to help him recover memories of his mother, Molly.

数据显示，在四个月内有58名孕妇死于生产，这意味着有58个年龄未知的混血体散落在外。混血体近来转入地下，这令Toby等人十分担忧。与此同时，病毒小组的工作取得了突破性的进展，他们正在研究新的病毒株。Molly也在试图查清John的死因，并找回Ethan。Toby帮Molly联系到了国土安全局相关负责人，但负责人表示由于Ethan并非人类，Molly想要回Ethan并非易事。

Molly panics when she discovers she is changing physically – the question is into what, and whether she can reverse what’s happening to her. Also, JD’s ex-wife, Dorothy, shows up suddenly on his doorstep to discuss their daughter.

Molly and JD try to convince Shepherd to broker a peace between humans and hybrids. Meanwhile, Lucy tries to manipulate Charlie’s feelings to put him in a compromising position.

Molly tries to save her son following a raid on the hybrid compound and JD tries to rescue his daughter from Shepherd. Elsewhere, Lucy becomes a bigger threat to humans.

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, JD and Ethan track down John’s mysterious former colleague who may hold the key to stopping the Humanich threat. Also, Julie enlists Charlie on a mission to find out where Lucy’s orders are coming.

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.