As Enterprise ventures deeper into the Expanse, the Xindi council continues to monitor its mission. The various members of the council also continue to disagree on the best course of action. The Xindi-Reptilians and Xindi-Insectoids are ready to take action against the humans, but Degra, the Xindi-Humanoid who is building the mysterious weapon, advises caution. The other Xindi species ultimately support Degra, agreeing that he needs more time to complete this weapon and that they shall proceed as planned.

Meanwhile, the crew of Enterprise is adjusting somewhat to life in the Expanse. T'Pol and Trip continue their Vulcan neuro-pressure sessions, while Archer determines that the ship needs to be insulated with trellium-D, a component that will protect it against the bizarre anomalies that permeate the Expanse. On a tip, the ship heads to an alien bazaar. Archer, Reed and Trip meet with a chemist named B'Rat, who can sell them the formula for synthesizing trellium-D. He also offers them a tip — the Xindi recently visited the bazaar. Determined to learn more, Archer visits the merchant the Xindi had business with. The merchant, Zjod, is selling alien women and one of them catches Archer's eye. Though the captain isn't interested in "purchasing" another being, he feels himself inexplicably drawn to this woman, Rajiin. Zjod — who doesn't seem to have any relevant information to offer — tries to bargain with Archer for the woman, but Archer is disgusted and decides to return to Enterprise. As he makes his way back to the shuttlepod, the alien woman runs after him, determined to escape Zjod, begging Archer to take her with him. After engaging in a brief fight with Zjod, Archer escapes the bazaar with the woman in tow.

Back on Enterprise, Archer tells the woman that Enterprise can return her to her home planet. The woman, who is called Rajiin, expresses her gratitude. Though she seems sincere, Rajiin also appears to have a few secrets. She visits Archer one night in his quarters, and he finds himself inexplicably mesmerized by her. As she seduces him, Rajiin runs her hands over his face and body, illuminating his physiology and anatomy — she appears to be taking some sort of scan. When she's finished, Archer snaps out of his trance and appears to have no memory of what has just occurred.

While Rajiin explores the ship, T'Pol and Trip attempt to synthesize trellium-D using the recipe from the chemist. In its liquid form, trellium-D is extremely volatile, so the duo has to be careful to follow the protocols exactly. Their first attempt ends with an explosion, so T'Pol suggests they get some rest before going back to work. Back in her quarters, T'Pol is surprised to find Rajiin, who performs the same strange scans that she performed on Archer. As she has a highly disciplined Vulcan mind, T'Pol is able to resist somewhat, and Trip shows up just in time to save her. Rajiin escapes and attempts to transport off the ship, but Archer catches her and sends her to the brig. Archer interrogate her, but Rajiin will only say that he is in danger and she does not want to see him harmed.

Just then, Reed alerts Archer to two Xindi-Reptilian vessels approaching. Archer deduces that they were the ones who sent Rajiin, and she insists that she had no choice. As the Xindi-Reptilians prepare to board Enterprise, Rajiin finally breaks down and tells Archer that she was sent to collect information about the humans for a bio-weapon the Xindi are building. A Xindi boarding party, consisting of both Reptilians and Insectoids, engages in battle with the Enterprise crew, who do their best to fend them off. Amidst the chaos, the Xindi take Rajiin back to their ship and one of the Xindi-Reptilians dies and is left behind. Archer attempts to pursue the Xindi ships, but they disappear into some kind of vortex. Frustrated, Archer can only order an analysis of the Xindi-Reptilian corpse and all the other data that's been gathered.

When the Xindi convene again, the other factions are furious with the Reptilians and Insectoids for their renegade actions. The Reptilians bring in Rajiin, who is able to provide the council with the biometric scans she took on Enterprise. With this new information, the Xindi now have the information they need to construct a deadly bio-weapon.