"Chuckhas almost reached the finish line, folks. The two-hour series finale airs on Friday, January 27 at 8 p.m. on NBC, and tomorrow night gives us "Chuck vs. the Bullet Train," either the next-to-last or third-to-last episode of the series, depending on how you want to look at it. (The two hour finale is made up of two separate episodes.) 

I'm going to have a whole lot of "Chuck" coverage next week, including a five-part retrospective interview I did with Chris Fedak and Josh Schwartz while I was in California. But before we start looking back, here's a chance to look forward with a sneak preview clip - exclusive to HitFix for the next few hours - from early in tomorrow night's episode. If you don't want to know anything before it airs (not that the clip gives much away), don't click through.

When last we left our heroes, Chuck had been abducted and Sarah, in a moment of desperation, had donned a pair of Intersect sunglasses to get herself and Casey out of an ambush. Of course, the last time we saw a hero on the show other than Chuck download the Intersect, bad things happen. So as this clip picks up, Ellie, Captain Awesome and Alex are running Morgan through some tests to see if there's anything they can see in his Swiss-cheesed brain that might help prevent the same thing from happening to Sarah.

Enjoy, and I'll be back tomorrow night at 9 with a review of the episode.

Alan Sepinwall has been reviewing television since the mid-'90s, first for Tony Soprano's hometown paper, The Star-Ledger, and now for HitFix. His new book, "The Revolution Was Televised," about the last 15 years of TV drama, is for sale at Amazon. He can be reached at sepinwall@hitfix.com