Improbable Causes, DS9 3
This episode has a little bit of every element needed to make a hardcore Trek nerd lose his mind. I love the Obsidian Order and I love the Tal Shiar. Garak is one of the most interesting characters on DS9 and to have a two-parter based on him is a godsend. Odo episodes are usually good, too. This has got twists and turns and lots of deep cut references to other shows. Plus, Paul Dooley back as Enabran Tain. Awesome.