This episode of “Lost” reveals the truth about John Locke and plants several other seeds that suggest the island we’re on isn’t peculiar only because it’s the home of a loud yet strangely invisible monster. A full report on “Walkabout” coming right up — but not before I check the cancellation policy for my Australian Walkabout tour…

“This is destiny. This is my destiny. I’m supposed to do this, dammit. Don’t tell me what I can’t do!”

If there is a single, series-definining episode of “Lost,” it’s almost certainly “Walkabout.” The final scenes, with their “Twilight Zone”-caliber revelation about the true story of John Locke that casts everything we’ve seen before in a completely new light, set the standard for many future revelations that precede the final LOST title card and clunking sound effect by only a few seconds.

So, full credit to the writer of this remarkable episode — not Damon Lindelof and Carlton Cuse, who have come to represent the “Lost” writing brain trust, but “Buffy” and “Angel” veteran David Fury. Fury’s writing stint on “Lost” lasted only one season, and appears to have ended in at least some degree of acrimony. (He ended up leaving the show to work on “24,” and forgive me for saying this, but what a colossal waste of talent that was. Perhaps there was simply no way for Fury to co-exist with Lindelof and Cuse on “Lost,” but “24?” I once admired that show, but when it comes to writing? Talk about your proverbial sausage factory.)

No matter the outcome, in many ways it’s Fury’s episode that not only forms the prototype of the very best “Lost” episodes to come, but in some ways it might be the episode that saved the show from cancellation. Think back to the series’ premiere in the fall of 2004. ABC first made the questionable decision of splitting the two-hour pilot into two separate episodes a week apart, but at least those two episodes deliver the goods. The third episode to be aired, “Tabula Rasa,” is a relatively mild look at Kate’s sojourn in an Australian farm. I’d be shocked if audiences weren’t getting a little antsy at this show with a strong action-adventure pilot that took its third episode to cool off and give us a little bit of a character study.

I’m not saying that I dislike the character-study episodes. On the contrary. I’m just saying, if you came out and told the ABC prime-time audience that your show about a plane crash on a deserted island was actually a series of character studies about a half-dozen characters and how their previous lives informed the decisions they made on the island, I think that audience would have abandoned the series in droves.

So with this pivotal fourth hour, we get “Walkabout,” and by its end we have a pretty good idea of every single scrap of clothing that’s been stuffed into the suitcase. This is a show about characters on an island, and about their pasts, yes. But those flashbacks are gonna blow your mind, man, and there is something seriously freaky about that island.

In case you haven’t gone back and consulted this episode, yes, this is the episode where we discover that Locke, who in the present is a wild-eyed guy with a suitcase full of knives who leads a boar hunt and ends up both confronting the island’s mystery monster and dragging a big ham dinner back to the beach, was a milquetoast in a wheelchair just days before.

The construction of the episode is beautiful, with a pair of bookended scenes of John on the beach wiggling his toes and putting on his shoes, flawlessly intercut with beach scenes from the pilot episode. In between, we learn about Locke, but almost everything we learn is almost immediately called into question.

Take the first flashback. It’s immediately preceded by a scene in which Locke hurls a sharpened knife and declares that the crash survivors will find sustenance by hunting the wild boars that attacked them the night before. As he’s about to spend more than a hundred episodes doing, Hurley asks the question we’re all thinking: “Who is this guy?”

Obviously he’s a military guy, given the phone conversation he’s having in the flashback, in which a co-worker calls him “Colonel Locke.” Except that’s immediately put to the test when his jerk of a supervisor, Randy, demands to see some TPS reports. (We’ll see Randy again — but earlier on in his timeline — as a co-worker of Hurley’s at Mr. Cluck’s Chicken. I believe the way the timeline works is, Randy loses his job when Mr. Cluck’s is destroyed by a rogue meteor, and in sympathy Hurley — who has won the lottery and owns the box company Locke works for — gives him a job at the box company. There’s your Obscure Lost Trivia for today.)

Randy (played by Billy Ray Gallion) is a really, really insulting boss. Why, if I were Locke, I wouldn’t take this sort of treatment sitting down. Hmm.

Locke leads the wild boar hunt (Wild Boar Hunt! In Color!), but his leadership skills are a little questionable. Michael gets gored, and rather than help Kate get him back to the beach, he just goes off in search of that white whale — er, pig. But not before a scene in which, knocked off his feet by the boar, Locke carefully moves his legs. There’s one shot in particular, of Locke’s foot in the extreme foreground as he checks to see if he’s okay, that really pays off when you watch the episode again. Yes, John, you can still walk. The miracle is still intact.

In Locke’s second flashback exchange with Randy, as well as the final scene with Locke in the office of the Australian Walkabout tours, there’s some pretty heavy dialogue that gives us an idea from the very beginning that Locke’s part of this story is going to be about fulfilling a destiny. In Tustin at the box company, he references a double amputee who climbed Mount Everest.

“That what you think you got, old man?” Randy says. “Destiny?

“Just… don’t tell me what I can’t do,” John replies, in the line that defines his personality. Later, after the Walkabout tour manager refuses to put Locke on this bus, Locke declares, “This is destiny. This is my destiny. I’m supposed to do this, dammit.”

The episode does give us what many of these episodes will — the hint that there’s more backstory to these characters without a lot of detail, allowing future episodes to fill in the blanks. In the case of Locke, we see — while he’s laying on his bed casually… hmm… — him talking to “Helen,” who turns out to be a phone-sex operator. Locke sadly proposes that she come with him to Australia. There’s much more story to tell here — later.

Similarly, he tells Mr. Walkabout Tours that it’s been four years since he lost the ability to walk. So this is apparently a recent occurrence. That’s interesting. I wonder what happened to make him suddenly lose the ability to walk? The show will, of course, answer that question. But not until we’ve sat through a series of teases and misdirections.

Speaking of teases and misdirections, it will be a long time before we catch a glimpse of the monster, let alone a long, full-frontal view of it. And we still don’t know exactly what it is, though there are some pretty good clues out there. But in this episode, someone does see the monster: John Locke. The monster comes at him through the woods, makes its creepy New York City taxi meter clicking noise, and apparently John passes the test in a way that, say, Mr. Eko won’t.

That scene — Locke sees the monster, turning his head from side to side in the suggestion that what he’s seeing is big — is one that stuck with me for a long time. It suggests that Locke either knows what the monster looks like or at least knows something about it. More importantly, the fact that he didn’t end up chomped like the pilot suggests again that there’s something special about Locke. But what? I think we have a much better answer now, but even given the outcome of the show’s fifth-season finale, I’m still not sure we’ve heard the whole story of John Locke. I sure hope we haven’t, anyway.

No matter Locke’s ultimate disposition, though, this episode’s ending is really a thing of beauty. Sure, the shocking revelation of Locke’s wheelchair in the tour office in Austrlia is what people remember. But that’s not how the episode ends. It ends with John back on the beach, Michael Giacchino’s score swelling in an uplifting manner that doesn’t match at all with the madness and horror of the plane-crash scene. John wiggles his feet, puts on his shoes, stands up, and rushes to help Jack (as seen in the pilot episode) — all mundane events were it not for the extraordinary events happening around him and the fact that for the past four years he hasn’t been able to stand upright.

In the show’s final scene, we’re back on the beach, as the survivors burn the fuselage. Through the flames, John spies his old wheelchair, and smiles. Wow.

Here’s the thing about this episode: It makes it clear that, from the very beginning, Locke is aware that the island is special. Not only does he know it because he’s been healed, but then he sees the monster. Locke is way ahead of everyone else. He’s not playing the same game as the rest of them, and it’ll be a long time before they catch up with him.

Now, there are plenty of other stories going on in this episode, despite all the Lockey goodness. It’ll be another season before the producers really put the island plot in stall mode. Right now, all the balls are in the air.

• The fuselage full of dead B-O-D-Y-S is dispatched, given a Viking funeral after a touching memorial service. Interesting points: Jack refuses to lead the memorial service, so it falls to Claire. Her makeshift memorial messages are a very touching reminder that a whole bunch of people died before the story of “Lost” even began. There’s Steve and Kristin, who don’t even have last names, but were in love and were going to get married. Some people are remembered based on the barest of details — video-store receipts, the corrective-lens and organ-donor indications on a driver’s license, and the lack of stamps on a passport. Perhaps the saddest of all: “Vonstead, Harold. That’s all we have, a name and a boarding pass.”

• Rose is a major guest-star in this episode. Jack is tasked with giving her a pep talk — wow, talk about the wrong choice. But it goes pretty well, considering. And we get that nice moment where Jack suggests she say something about her husband, and Rose looks at Jack like he’s certifiable. “Doctor, my husband is not dead,” she says — another one of my all-time favorite “Lost” lines. Jack responds by telling her that everyone in the tail section is gone. Rose’s response? “They’re probably thinking the same thing about us.”

• Another interesting thing about Rose: As we’ll find out later, her story parallels Locke’s. She, too, has benefited from the miraculous healing powers of the island. How fitting that she should be featured in this, of all episodes. But Rose, unlike Locke, is not interested in making a journey of discovery and destiny. She’s satisfied with finding her husband and living out her natural life with him on the island. Sounds good to me, Rose.

• Sayid’s quest, in his role as Iraqi MacGyver, is to fix the radio. We see him working on it in this episode, and it’ll lead to him meeting Danielle Rousseau in a few episodes. It also leads to him giving Kate an antenna to place in a tree, which she completely botches.

• Boone and Shannon bicker some more. They really are this season’s Nikki and Paolo. Also, Shannon proves herself to be a gold-plated bitch by conning Charlie into getting Hurley to catch a fish. This will set up a story arc in which we learn that Shannon is a misunderstood soul just waiting to be redeemed by the love of a former Iraqi torturer. Boy, can’t wait for that.

• Claire finds Sayid’s photo of Nadia in the personal effects.

• Sawyer gives some stuff to Claire, suggesting he’s growing a conscience. Which is sort of a misdirection, and sort of not.

• Boone shows concern for Locke — “That bald guy didn’t come back!” — that you could call foreshadowing of his relationship with Locke if you really wanted to.

• The episode’s other big “Twilight Zone” element — which sort of gets paid off in the following episode — is Jack twice seeing a man wearing a business suit and white tennis shoes, looking at him from far off down the beach. Both times he disappears mysteriously, as apparitions do. This ends up being pretty darned relevant to the series’ story arc as a whole.

Which brings me to one of the major questions about “Lost,” namely what the writers knew and when they knew it. David Fury himself claimed that the writers didn’t have a clue and were making it up as they went along. I believe that statement was mildly disputed by Cuse, Lindelof, and J.J Abrams.

Do I really believe that the writers knew where they were going at this point in the series? No, of course not. I think they had some general ideas, but also wanted to plant some seeds that could be used later as payoffs, even without knowing exactly how. A lot of fans would call this retcon, or retroactive continuity. But I don’t think that’s fair. Locke’s healing and talk of destiny, his ability to stare the monster in the face without perishing, shows that the writers knew what direction they were heading, but not necessarily in more than the vaguest terms. Likewise, the reference to the tail section — another thread intentionally left loose. This early in a series’ run, the last thing you want to do is close yourself off from possibilities. So the writers created a lot of compelling-but-vague mythology and figured out how best to fit it in later.

My best bet is that Cuse and Lindelof really figured out where they were going after the first season, when the show’s ratings suggested they’d have a chance to run for years. But as I watch these episodes again, it’ll be interesting to note which threads they’ve picked up — and which ones they’ve ignored.

Another interesting topic brought up by this episode: In many ways, the revelation of Locke’s magical healing powers is the final admission from the show that it’s going to have a serious fantasy element. (Yes, the monster and polar bears were big hints, but they could have been explained away by more mundane answers.) It’s always a delicate thing, asking a mainstream TV audience to accept that you’re telling a story that’s got rules a bit beyond accepted reality.

Now, why this should be the case is something that causes me some consternation. Most blockbuster movies are fantasy or sci-fi. Many bestselling novels, including those by “Lost” patron saint Stephen King, also deal with fantastic premises. But sci-fi on mainstream network TV doesn’t have a great track record.

“Lost” gets away with it, I think, because of its modern setting and its emphasis on character. At the end of the episode, the impact we feel when we see Locke in that wheelchair is far greater because of who he is and what we’ve seen about his life on and off the island. In that moment, yeah, we’re wondering how he was magically healed. But we’re also realizing that when John Locke truly got a chance to fulfill his destiny and have his adventure in a wild, far-off land, he ended up dragging a boar back to camp and feeding all of his compatriots. That’s the brilliance of “Lost.”

Skippable? Are you kidding? If you could watch only one first-season episode of “Lost,” this might be it.

Superfluous: Kate shows that she’s a wicked good tree climber. This will never be important.

Up next: “White Rabbit,” in which Jack goes down the rabbit hole and we meet Christian Shephard and a remarkable facsimile.

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