Archer and the crew are startled to discover the Vulcan High Command has ordered T'Pol to leave Enterprise and are equally frustrated at her seeming indifference about reassignment. However, T'Pol's last mission as a Starfleet officer proves eventful when a militant faction on Coridan, an alien planet, kidnaps her and Archer. Aid comes in the form of the mercurial Andorians: their leader, Shran, still owes Archer a debt (from the events of "The Andorian Incident"). The Vulcans are covertly backing the ruling faction on Coridan, while the Andorians are aiding the freedom fighters. With the help of the Andorians, Malcolm and Trip rescue Archer and T'Pol over the objections of the Vulcan ship retrieving T'Pol, and Shran considers his debt to Archer repaid.

En route to the eye-catching Arachnid Nebula, the crew encounters an obsolete Vulcan vessel manned by the Vahklas, a Vulcan sect that embraces emotional impulses. Despite her misgivings, T'Pol allows her curiosity about their lifestyle to get the best of her.