As a trained apothecary – so skilled at her job that her facilities even impressed T'Pol despite their primitive standards, Phlox reflecting that she would have been a fine physician if she'd been born on Earth or Vulcan – she was involved in researching a mysterious disease that killed her brother. She believed that a curio shop run by Garos was the source of the epidemic that was spreading among her people. She and a disguised Archer, who had arrived on the planet to explore and observe its pre-industrial civilization, discovered that Garos was really a Malurian whose mining operations contaminated the planet's water supply.
Riaan and Archer had a brief romantic relationship before the latter left the planet, Archer assuaging her fears at seeming backward to the space-faring Humans by noting that without their technology they were really rather similar. (ENT: "Civilization")