Tonight was a pivotal moment in the final season of "Lost," which should come as little surprise since tonight was the return of Desmond Hume to active duty.

"The Constant" is a dividing point for many fans.  The ones who hate the time travel and the alternate timelines and the donkey wheel... well, "The Constant" is pretty much enemy number one for them.  And I can see how if you don't like the way the "Lost" writers play with those ideas, the last few seasons must feel like a major letdown after getting invested in a story that was laid out, for all its mysteries, in a fairly simple and linear manner.  One story on the Island, one story in flashbacks.  People trying to survive, and the things that haunt them from their past.  There was a shape to it that was fairly comfortable.

And then the show exploded.  Literally.  Timelines fractured.  Structure caved in on itself.  And it became a very different show.  The characters are all still there, and we are definitely still dealing with story threads that were introduced five or six seasons ago, but so much more has happened since those early seasons that we're starting to realize now that we're not watching the show we initially thought we were watching.  And that can be a disconcerting thing for a viewer, no doubt about it.

This season in particular has been an upset for some people thanks to the flash sideways storyline that's been the subject of much debate since the season premiere.  I've read reactions calling the alternate timeline "confusing," "pointless," and "a train wreck."  I've also read reactions from people who have been engaged by the puzzle presented to them by the show this year, at least a half-dozen different interpretations of what they're watching.  I've certainly speculated about the nature of what we're seeing openly here in these recaps, and my theories have evolved over the course of the season.  I've used a shorthand while describing the separate storylines, referring to one as TIMELINE A and one as TIMELINE B, although I'm fairly sure it's not as simple as a rift in time or space.

Tonight's episode was written by Damon Lindelof and Carlton Cuse, which should automatically tip you off to the overall significance of the episode to the mythology, and it was a triumph for the series, bringing several major players in the series to center stage again after sidelining them for a while, and the way they did it seemed to me to fold the show's reality in on itself in a fascinating way.

There was no "previously on" montage at the start of the show.  Instead, the show simply began with Desmond waking up in TIMELINE B.  Zoe explains to him that he's not in the hospital anymore.  Desmond wants to know where his wife is, but before she can answer, Charles Widmore steps in.  And although it has only been a few days in the continuity of the show, it's felt like forever for those of us watching the show since these two were face-to-face.  Widmore tells Desmond that he was shot by Benjamin Linus, and that he's been brought back to the Island.

Desmond's reasoned, considered response to this information is to savagely beat Widmore with an IV stand.  Fair enough.

In the first of this episode's many echoes, which have a thematic purpose beyond simply making fans say, "Hey, I recognize that!", comes when Widmore tells Desmond "The Island isn't done with you yet."  It rattles Desmond to hear it, and it seems to rattle Jin as well, who listens from the doorway.  He wants to know why Desmond's back, and Widmore tells Zoe to take Desmond to the generator room so they can "start the test."

We see that Babyface Henchman is helping set up the generator for the Hydra Station, and that something's been set up outside, a free-standing room with a number of electrical cables running into it.  They mention trying to generate an "EM field," and how they're going to test it on a rabbit.  Instead, a dude fixing it gets fried when the generator kicks to life at the wrong moment.  When Des sees the smoking corpse in the room that they're about to push him into, he goes nuts again.

And then we get the opening LOST.  Quite the way to kick things off, and it really doesn't even hint at what the episode's got in store for us.  It's one of those where every line of dialogue feels significant.  Desmond gets locked in that room with the crazy coil things on each end, while Widmore tries to explain to Jin what they are about to do.  "That man is the only person on Earth to survive a catastrophic electromagnetic event, and I need to know he can do it again."

That combined with Widmore telling Desmond that he's going to ask him to make a sacrifice if things work out suggests to me that this week's title is just plain cruel.  Desmond and Penny were given a happy ending two years ago, and it was one of the greatest emotional beats in the series so far.  It's a betrayal for those of us who were invested in that happiness just as much as it's a betrayal for Desmond and Penny to have him brought back to the Island and to put him in a position where the only way to save everyone is to put an end to that happiness.

Widmore turns on the coils, and Desmond begins to thrash in pain.  As the coils cycle up, Des starts to spasm, and then suddenly he vanishes in a burst of white and then...

... clouds.

And we're in TIMELINE A again.  The alternate life where the season began.  The reality in which Desmond Hume was on Oceanic 815, and landed in Los Angeles with the rest of the characters.  Most of the rest of the episode plays out in this timeline, and we get a long look at the way this world works, and in the process, we finally see the seams in things.

Desmond runs into Hurley and Claire at the baggage claim, and then runs into George, the character played by Fisher Stevens.  When he first appeared on the show, he was onboard Widmore's freighter, and he got stuck bouncing between timelines, eventually dying from the process.  Here, he's a limo driver, and he's been hired to drive Desmond to the office of his boss.

That boss, it turns out, is Charles Widmore.

Desmond doesn't just work for Widmore in this timeline, though.  He's his right-hand man, the guy Widmore turns to when there are problems that need solving.  In this case, Widmore's wife has the problem.  She organized a charity event that her son is going to play at, and he requested a specific band to play with him at the event.  Is any "Lost" fan surprised that the band is Driveshaft?

Problem is, Charlie OD'd on the flight, as we saw, and he's in jail.  Widmore wants Desmond to bail him out, then babysit him until the event to make sure that Driveshaft plays.  Desmond's happy to do it.  Once that's settled, Widmore goes to pour a couple of drinks.  "You really do have the life, son," he says.  "No family.  No commitments."

Desmond agrees.  "I"m a blessed man, sir."  Widmore pours him a shot of that 60-year-old Scotch that he refused to share with him when we first saw these two together in Widmore's office.

"Nothing's too good for you," Widmore tells him.  It's obvious by this point that this timeline isn't just an alternative to the "real" world of the show... it's a construct with an agenda.  I've said now for a few weeks that what we're seeing play out are the results of some sort of a deal that's been made, where people are living out lives that fulfill some need, some desire, although not in the ways they thought.

The episode really kicks into a new gear when Desmond picks up Charlie from the courthouse.  Charlie's an angry little zombie at first.  He doesn't seem to care about anything, and barely notices Desmond at first.  They go to a bar where Charlie talks about what happened to him on the flight, where he saw the face of love.  This is the crack in reality we've been waiting for, proof that this isn't just some cleverly time-shifted coda to the show, but a false reality.  Desmond's unimpressed by the way Charlie describes a vision of Claire, but I found it really moving.  Dominic Monaghan may have checked out of this show early, but he left a hero, and this return only cements him as one of my favorite things about "Lost."

When they leave the bar, Charlie can tell that Desmond still doesn't understand.  "How about I give you a choice?" he asks as Des drives.  "I can either show you what I'm talking about, or you can get out of the car."

He grabs the wheel and steers them off the road, into the ocean, and as the car fills with water, Desmond struggles to get loose.  He swims to the surface, catches a breath, and goes back for Charlie.  Even before it happened, the hair on the back of my neck stood up.  I knew what we were about to see.  It was impossible to miss the echo.  Desmond on one side of the glass.  Charlie on the other, about to drown.  And as Charlie raises his hand, there's a flash, and for a moment, Desmond sees something written there.  "NOT PENNY'S BOAT."  And the Charlie he's looking at isn't the same Charlie.  But it is.  But it isn't.  And then the flash is over and Desmond pulls Charlie out and up to the surface.

Okay.  Seriously.  That's one of those moments that only TV can pull off, because without the investment of years in the fates of these characters, the Charlie moment wouldn't have packed the punch it did the first time around, and seeing it again like this, as a crack from one reality to the next, wouldn't have felt like being hit by a car.  I played it twice just to watch how perfectly timed and staged it was.  Exceptional.  And it was really just the start.

At the hospital, as Desmond's being put into an MRI for some tests after the car crash, the lab tech asks him if he has any metal on him, a direct echo of a line earlier in the episode as they were putting Desmond into the crazy EME coil room.  As the MRI starts, Desmond gets more of those flashes, this time actually seeing Penny.  And not just a glimpse of her, but a wave of images and emotions.  Suddenly, he remembers this other life.  This happiness that is so alien to him in this timeline.  And it freaks him out.  He goes looking for Charlie, running into Jack in the process.  Charlie goes running by, obviously dealing with his own freak out.

Desmond chases him, a white rabbit in a hospital gown, finally cornering him and demanding answers. Charlie can tell that Desmond's had a vision, just like him, and he tells Desmond that he can't deny the reality of what happened.  "This doesn't matter.  None of this matters.  All that matters is that we felt it."  Desmond is at a loss for how to continue or what to do about these images in his head, and he thinks Charlie can help him.  Charlie tells him he's wrong, though.  "Stop worrying about me.  Start looking for Penny."

That's exactly what the rest of the episode deals with.  Widmore's angry about Desmond losing track of Charlie, and he tells Des to go explain it to Mrs. Widmore himself.  When Desmond goes to do that, it turns out that Eloise is Mrs. Widmore.  Des is ready for her to be a huge ballbuster, but she seems unphased by the news that Driveshaft won't be playing.  "What happened, happened," she says.  It's almost like all of these echoes are picking up steam at this point as reality starts to get thin.  Desmond is about to leave when he hears someone reading off the guest list and hears the name Penny.  Desmond asks if he can look at the list, and the request seems to suddenly enrage Eloise.  She takes him aside, and one of the best conversations of the season so far ensues.

"Stop talking, Hume.  I've heard what you have to say.  Now you listen to me.  I want you to stop."

"Stop?  Stop what?"

"Someone has clearly affected the way you see things.  This is a serious problem.  It is, in fact, a violation.  So whatever you're doing, whatever it is you think you're looking for... you need to stop looking for it."

"Do you... do you know what I'm looking for, Mrs. Widmore?"

"I don't know you're looking for anything.  You have the perfect life, on top of which you've managed to attain the thing you wanted more than anything... my husband's approval."

"How do you know what I want?"

"Because I bloody do!"

"I need to see that list.  Or you need to tell me why I can't."

"You can't because you're not ready yet, Desmond."

"Ready?  Ready for what?"

So much said.  So much suggested.  So much promised, and just a few episodes left to pay it all off.  If that conversation was the end of the episode, I would have been left reeling.  But no... no, "Lost" has to play one more trump card.  Desmond makes it back out to the limo, and he's about to leave when someone knocks on the window.  It's Mrs. Widmore's son, the musician who wanted to play the gig with Driveshaft.  Daniel Widmore.

Seeing Jeremy Davies back makes perfect sense.  He and Desmond have been connected on the show in the past, and it turns out he's seeing the same flashes that Desmond and Charlie are seeing.  Just as Charlie's glimpses are focused on Claire and Desmond's glimpses are focused on Penny, Daniel's were triggered by the sight of Charlotte in a museum.  Love is indeed the Constant on "Lost," and when Daniel was jarred by his encounter, he suddenly started writing out long, complex quantum mechanics equations.  He ended up showing the equation to a friend at a university, who explained it to him.  The equation describes the way energy can be dispersed, like the detonation of a nuclear bomb, to prevent an impending catatstrophe.  And as Daniel describes it, he poses a question.  "What if all this wasn't supposed to be our life?  What if, for some reason, we changed things?  I don't want to set off a nuclear bomb, Mr. Hume.  I think I already did."

He gives Desmond another piece of the puzzle, too, telling him that Penny is his half-sister, and telling him where he can find her.  The stadium where he goes to find her running looks awfully familiar, and he watches her jogging for a moment before introducing himself.  When he reaches out to shake her hand --

-- he wakes up in TIMELINE B on the floor of the EME room.  He can still feel Penny's touch.

He's unhurt.  He survived the test.  He was only unconscious for a few minutes, and as they check him out, Widmore starts to explain what he wants Desmond to do.  Des cuts him off, though.  "I understand."  He's ready to help.  Calm about it.  Accepting.

As Zoe walks Desmond back to where he'll stay, they're jumped, and Sayid kills the guy who is with them.  Zoe runs off, and Sayid tells Des that they need to go.  Just as he was with Widmore, Des seems calm, unruffled by anything.  "Aye, of course.  Lead the way."  Somehow, I don't think the Man In Black is going to be particularly happy to see Desmond on the Island.

In TIMELINE A, Des wakes up where he fainted.  Penny's there, concerned.  He asks her out for coffee, floored by her, and she agrees to meet him later.  Once he's back in the limo, George asks Desmond if he found what he was looking for.

Desmond seems happy.  At peace.  He tells George he needs a favor.  He wants him to track down the passenger manifest from Oceanic 815.  George says he can do it, but he asks why.

With a smile that will haunt me all week, Desmond replies, "I just need to show them something."

With a Hurley-centric episode coming next week and a fair number of the cards on the table, I have a sinking feeling that "Lost" is about to start hurting us.

And I, for one, can't wait.

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