After years of struggling with infertility, astronaut Molly Woods is finally pregnant. But with what? Molly continues her charade with her husband John, neglecting to tell him that she's pregnant. But how can she fess up when she's not sure what to say?
Meanwhile, Molly and John's son, Ethan, a Humanich, is getting ready for his first day at school. While playing outside, Ethan traps a bird in a self-made contraption and listens to it struggle. He always seems a shade away from normal.
On Ethan's first day, other parents are concerned about sending their children to school with a Humanich. But Molly stands up for Ethan, assuring the parents: "He's not dangerous. He's just different." There's no reason to be afraid of Ethan. Yet, the question lingers. Has Ethan really learned how to be human by living with Molly and John? Or is he a kettle ready to boil?
Later, Molly runs into Commander Sparks, who reveals that Molly was impregnated with samples from both her and John during secret medical testing ran by the ISEA (International Space Exploration Agency). Sparks urges Molly to get a day or two of medical testing in the lab, since her brain waves are matching her former colleague Kryger's, which showed he had hallucinations right before he supposedly committed suicide. Molly just got back from her mission and is reluctant to leave her family. She puts Sparks off, for now.
Molly visits Kryger, the lost astronaut who Molly knows is not dead, but hiding out in secret. Harmon's not at home but Molly finds an intriguing pattern of circles on the wall, which look just like the circles that emerge from her stomach when she has morning sickness.
John decides to throw Molly a birthday party, to celebrate what they missed while she was in space. At the party, Molly's friend and doctor, Sam, draws blood from Molly to test in the lab. Alone for a moment, Molly is surprised by Tim, the brother of her ex-boyfriend (who's since passed away), Marcus.
John finds Ethan's captured birds and instructs him "no more secrets." Ethan spills the truth - his mother has a secret. Molly tells John she's pregnant. And it's theirs. Molly's fear of the unknown is compounded when she learns that Tim wasn't at her party - he was a vision, just like her earlier hallucination of Marcus. Molly decides to take Sparks' advice and let him drive her back to the lab for medical testing. But Molly gets a sudden text from her friend Sam, telling her to get out of the car. She's not safe with Sparks. There's more than he's telling her. Molly's able to jump out of the vehicle and is surprised to find John there, ready to save her. But is she jumping to safety? Or just the unknown?