 A group of Kreetassans are on board of Enterprise for a friendly meeting. But they leave rather unexpectedly as they seem very offended by something. The crew have no idea what however. But as their ship leaves an alien gel like creature manages to crawl aboard. The creature is growing and growing and shows rather hostile tendencies as it encapsulates five crew members, including captain Archer and commander Tucker. T Pol, Hoshi and Reed have to come up with a solution quickly. The lives of the five are at stake as the creature begins a symbiotic relationship that in time can t be reversed.