Season 4, Episode 7: When Earth's embassy on Vulcan is bombed, the investigation puts Archer and T'Pol on the trail of a Vulcan religious faction hiding in a treacherous desert. 

We close a chapter in Trek history (and the Willennium) with the show that started Lauren's journey into Trekdom. She takes the captain's seat this episode, plays the piano, and finally puts to bed Mario's anti-Enterprise rhetoric!

Hear how CSI and turn of the century fearmongering factor in if
I'VE NEVER SEEN STAR TREK!