Enterprise recovers a dying alien from a pod near the spheres, while Reed and Hayes come to blows and Tucker and T'Pol become intimate.
Near a cluster of spheres, Enterprise recovers a pod holding an alien that cannot survive in normal space. Phlox struggles to keep it alive, and when it revives it phases through the ship's walls toward the warp core before Reed and Major Hayes stop it. It declares that its people will prevail once the Xindi destroy Earth, then vanishes. Its kind are later revealed as the Sphere Builders.
Meanwhile, Reed resents Hayes's push for joint training, and their rivalry ends in a fistfight. Tucker's friendship with a MACO, Corporal Cole, stirs T'Pol's jealousy, and their neuropressure sessions turn intimate, though T'Pol later treats it as an experiment. The episode was directed by David Livingston, with a teleplay by Manny Coto.