Racing against time, Rachel and Lily are forced to make a decision that could alter their lives in order to save humanity.

Rachel continues to seek information regarding the virus, while also managing an alarming situation in Lily's life. Meanwhile, Zach is under scrutiny at the CDC.

Rachel enlists Lily's help with an important task in order to further her mother's medical research into a cure. Zach learns surprising information from his CDC colleague and former lover.

Rachel attempts to coax confidential CDC information from Zach. Lily tries to continue pursuing her career dreams despite the chaos.

Lily figures out what to do with her dangerous client. Rachel attempts to gather evidence from her various patients to present to her husband, who works at the CDC.

While conducting telehealth appointments from her New York City brownstone, Rachel tends to one of her patients with an strange injury. Upstairs, Lily finds herself in a risky position with one of her clients.