Terra Prime holds Earth hostage and puts a human-Vulcan baby at the centre of a standoff.
Terra Prime seizes the verteron array on Mars and threatens to fire it at Starfleet Command unless all aliens leave Earth. Paxton also captures Tucker and T'Pol, and he uses their infant clone, a daughter, as proof of the dangers of human-alien mixing.
Archer leads a team to infiltrate Paxton's base, and the array's shot misses Starfleet Command. The baby dies of a genetic defect, and Tucker and T'Pol grieve, naming her Elizabeth. Archer gives a speech that helps the coalition talks move forward. The episode was directed by Marvin V. Rush, with a teleplay by Manny Coto.