On board Enterprise, the Universal Translator has resulted in a minor diplomatic incident with the Kreetassans. Later, Ensign Sato analyzes their language and finds that each word can have a dozen meanings depending upon its context. As the Kreetassan vessel departs, a clear, amoeba-like entity crosses to Enterprise, and systems begin to malfunction on a ship-wide basis. Crewmen Rostov and Kelly are both trapped in a cargo-hold by the entity which has now grown tendrils. Captain Archer, Commander Tucker, Lieutenant Reed go to investigate and are all caught as well, except Reed who escapes through the cargo-hold-hatch, severing one of the tendrils in the process.
Ensign Mayweather suggests tracking the Kreetassans down to ask about the entity, while Doctor Phlox examines the severed tendril. He determines that those entrapped are becoming symbiotically linked together through the entity. Sato wants to communicate with it, but Sub-Commander T'Pol decides to neutralize it instead. Mayweather manages to find the Kreetassans, asking for any information they may have. They agree to share the location of the entity's home world, but only after Mayweather apologizes for the earlier incident. Apparently the "misunderstanding" occurred when the Kreetassans were taken to the mess-hall to find many of the crew eating in public, which they regard as vulgar.
T'Pol, Sato, and Reed make their way to the cargo-bay to attempt communication. Reed assembles experimental force-field-emitters, which are able to protect them from the entity's tendrils. Sato uses the Universal-Translator to modulate a frequency that the entity can understand. After several attempts, the entity responds. It gives them new, more precise coordinates on its home-world, and Phlox notices that the bio-signs of the trapped personnel are stabilizing. The entity then releases the personnel, shrinking back to its original size. On the entity's planet, both organisms are released and are quickly re-absorbed into a larger alien body. As the shuttle-pod returns to Enterprise, dawn breaks and the entire area is revealed to be covered with a single huge organism.