When Enterprise diverts to investigate an unusual planetary phenomenon near Earth, Mayweather visits his family after the sudden death of his father, a cargo-ship captain. But his return to his old home, the ECS Horizon, is complicated by family tension. He clashes with his brother, the ship's new captain, and pirates attack the ship. Meanwhile, Archer and Trip invite a reluctant T'Pol for movie night to see Frankenstein and find her reaction surprising. She says she will suggest Ambassador Soval show the movie to every Vulcan newly arrived on Earth.

The Enterprise crew makes first contact with the Vissians, a species with three genders. Trip meets one of the species' third gender, a Cogenitor, a being used for only breeding purposes. After learning how badly Vissians treat all Cogenitors, Trip attempts to help this Cogenitor, even though it directly interferes with Vissian culture.