Molly tries creating a virus to destroy alien hybrids and discovers that aliens are trying to communicate with humans through a hidden message in their DNA. Elsewhere, Lucy helps Ethan run away from Charlie to help him recover memories of Molly.
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; and Julie struggles with Ethan's rebellion.