After analyzing the artifact from Lyrek, Adira and Tilly find that the spots on it match with those of a Trill scientist named Jinaal Bix, who lived 800 years ago. As the Discovery arrives at Trill, Guardian Xi only permits the away team to beam down after Burnham has answered the question that the fourth stanza of the Romulan poem leads to Betazed. Kalzara, the current host of the Bix symbiont, and Hugh Culber undergo the zhian'tara in the Caves of Mak'ala, so Jinaal can lead Book and Burnham to the clue. Jinaal, Vellek and four other scientists found the Progenitors' technology but it was so overwhelmingly powerful that they decided the galaxy was not yet ready for it. In the meantime, Rayner gets acquainted with the crew of the Discovery on Burnham's orders, but he doesn't make friends among them with his callousness. After talking to Duvin, a Vulcan advisor, Saru is concerned that her engagement to an outworlder may endanger T'Rina's political career and Vulcan purists could gain influence. Saru suggests to postpone the announcement. Yet, T'Rina says she has nothing to hide and convinces him to proceed regardless. As Book, Burnham and Jinaal, in Culber's body, proceed to the stash, they are attacked by indigenous predators. Jinaal chooses to retreat. Book and Burnham keep trying and get trapped. They recognize that the creatures only try to protect their clutch and are free to leave after successfully communicating that they mean no harm. They return to Jinaal with the intention to try again later, but Jinaal says this was a test and hands them the next puzzle piece (which leads into Tzenkethi space). As Adira is still on Trill to say goodbye, Moll sneaks in and secretly attaches a transponder to their uniform.