Piper Maru

A key episode that introduces one of the most important features of the series- the black oil- yet it also is extremely Scully-centric. In fact, I feel like they have Mulder running around in the background just to that he has something to do while Scully a) learns that her sister's investigation is being put on old, b) heads back to her old stomping grounds and c) gets the whole story about the original salvage attempt.

That doesn't prevent these two from having some great moments. The first is when Scully first enters their office after learning the bad news about her sister. She doesn't say anything to him about that, but he senses everything is not alright. Surprisingly she turns herself around and lobs some good natured teasing his way, followed by a cleverly hidden compliment about his refusal to back down.

S: I'm just constantly amazed by you.. you're working down here in the basement, sifting through files and transmissions that any other agent would just throw away in the garbage.

M: Well that's why I'm in the basement Scully.

S: You're in the basement because they're afraid of you, of your relentlessness and because they know that they could drop you in the middle of the desert, and tell you the truth is out there, and you would ask them for a shovel.

M: (maybe mildly wounded) Is that what you think of me?

S: (smiling at him) Well, maybe not a shovel. Maybe a backhoe. 

Mysterious radiation burns have taken out the entire crew of a ship sent to recover some salvage. Oh and PS, the diver has been taken over by the black oil/alien virus. Sweet action! M & S investigate the wreckage that everyone has been scrambling for by going to the ship itself and checking out the recording from the diver's camera.

MORGAN: What the hell is that?

M: Looks like the fuselage of a plane.

S: It's a North American P-51 Mustang.

MORGAN: Yeah it sure is.

M: ... I just got very turned on. 

Sadly, this is the last they see of each other while Scully heads to an air force base to question a friend of her fathers. She gets a bit misty when she pictures herself and her sister playing together as children. 

I know how much she misses Melissa, but no one has this much fun playing hopscotch.... ok maybe me and my sister would...

And Mulder follows a lead from the diver's house, to a sketchy salvage yard, then on to Hong Kong of all places. And guess who is there?

Kick ass! Mulder proceeds to kick the shit out of him, for obvious reasons, not the least of which being Krycek killed his father.

Meanwhile, Skinner is threatened in a restaurant that he seems to frequent for breakfast. The following day he is shot in an apparently random but actually not-random-at-all hit. It's the asshole who shot Melissa! 

Back in Hong Kong (can't write that every day), Krycek encounters a woman in the men's room. WTF right? Well, the clues all lead to Hong Kong, but the black oil went there too, in the form of the diver's wife. It's come a long way just to be led to Krycek, who in turn can lead the oil back to a space ship, where it belongs.

Killer.