This series is wrapping up its run in a few more weeks. Really sad too but it's the nature of network TV, all be it we're talking about UPN. There are plenty of episodes which allows us to recognize places, things, and species from the other pieces of the Star Trek universe. For example, we see Andorians, Vulcans, Romulans, Rigelians, etc. He hear about Delta, Enterprise was going to Babel, and this episode which I just saw last night takes us to the 22nd centuries alternate universe.
Admiral Forrest is in command of Enterprise. Archer is the first officer. T'Pol is very sex and is a loyal Vulcan slave of the Terran Empire. They go into the Tholian system and for the first time in modern Star Trek history we see an actual tholian (computer animated, but it's a Tholian) who is eventually tortured to death.
The Imperial Ship Enterprise makes a discovery in Tholian space. I could tell you but you would not be compelled to watch. If you want to know watch the next episode. If possible go to your Star Trek history books to the third season of the original series and make a guess. Remember this is an alternate universe.