Of interest to lovers of green people everywhere!
Okay, so this is the Orion Slave Girl episode. The Orions previously appeared in the original series (via Orion Slaves Girls), and popped up earlier in the fourth season during the Augments Trilogy, but this is the attempt to turn the Orions into Enterprise's next Andorian project, explaining more about a culture that stood out a long time ago but hadn't been seen since.
You learn, basically, that those Slave Girls are actually in control of their husky males. A matriarchy of hookers. Who would've guessed? (Other than Barney Stinson.)
There's token attention paid to Trip and T'Pol's complicated relationship, but that's basically what this one is about. Whether or not you find this as another excuse for Star Trek to feature scantily clad females is entirely up to you.
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Memory Alpha summary.