There is alot going on in this episode. At its core is A Chase story - where T'Pal (protaganist) is after a former Vulcan agent altered to work undercover in on an alien world.
Essentially, the chase, cornering and subsequent interrogation of the target allows for a great big dose of character development for T'Pal and some for Archer and Travis. The major event is that we the viewers see the trust and bond between T'Pal and Archer continue to grow.
The first act sets up the mystery as to why this person is actually wanted by the Vulcan High Command and what this person did. We are cleverly led to believe that there is more to the situation and the reason for this antagonists capture, through their recounting of events and T'Pals powerful flashbacks and what the Vulcan priest did to her to make her forget.
The real interest maker in this episode is who the screenplay develops to make events of the past and present ambiguous and therefore, sway viewer emotions from believing one thing and then something else.
I found the setting to be fabulous, an sorrid den of drunk loner, outsiders and troublemakers. Pacewise, dont expect many fireworks, but the script really does a great job of generating interest and providing a strong emotional attachment to the situation between the characters.
The end is genuinely exciting, if a twist on a theme for those of us who have watched too many SF programmes and provides a suitable conclusion for what is a fine example of this show.