Borderland, Cold Station 12, The Augments
Thanks to Netflix, I've been catching up on my Star Trek, with both Voyager and Enterprise.
So far, I've found another multi-part episode that rivals "Through a Mirror Darkly", and that is the three part arc of Borderland, Cold Station 12, and The Augments.
This, quite simply, was "The Wrath of Khan" for Enterprise. I thoroughly enjoyed every minute. Brent Spiner was great as Noonien Soong, and Alec Newman (who played Paul Atreides/Muad'Dib in the Sci-Fi Channel productions of Dune and Children of Dune) was very effective as Malik, the augment who rebels first against his brother, Rakiin, and then against his own creator/father, Soong.
Involving the Klingons was perfect, as it occasionally served to complicate things for Archer and crew. The episodes struck the perfect balance of overall story, and interpersonal story that Wrath of Khan so deftly wove.
For me, this was 2 hours and 15 minutes of pure entertainment, right up to the final moments. I could watch this and "Through a Mirror Darkly" back to back, and be satisfied that I've probably found some of the best that Enterprise had to offer.