The pickup truck rumbles over the stream of rubble that passes for a road, and we splash full-on into the river. With a bit of wheezing and complaining, the engine holds out and we push on across to the other side. It's official now: we've crossed the border. Illegally.

Lek is fiddling with the knobs on the radio. Letting out a whoop of satisfaction, she lets it come to rest on the only station we're able to receive out here. Even I can tell that the music filling the cab of the truck isn't being sung in Thai.

She flashes me a huge smile. It's odd that just a few weeks ago, I knew her only as someone being interviewed in a National Geographic documentary. She's the founder of Elephant Nature Park, one of the most inspirational people I've ever known. And her good moods are tremendously infectious.

"Tim," she yells to me over the noise of the radio, "we're in Burma now! Are you exciting?"

Her English is generally first-rate, which only serves to make her occasional slip-ips that much more endearing. "Yes, Lek, I'm very exciting."

I pause for a moment. Squinting out at the spectacular landscape around us, I realize that only one thing is keeping this from being perfect.

I wish Jessica was here right now.

"Do you think we can handle this?"

I'm still struggling to get my mind around everything. Less than a month ago, we arrived here at Elephant Nature Park as day visitors. Now, four weeks into our one-day excursion, we're sort of being put in charge of the place.

Michelle, the Australian firecracker who normally leads the tours and manages the volunteers, is back in Melbourne on vacation. Her husband Karl, who is the park's only western mahout, is on his "border run" (crossing out of Thailand briefly and then back in, to renew his one-month visa). Michigan native Jodi usually splits her time between looking after elephants and looking after her 18-month-old son Raki, but she's been leading the tours while Michelle's been away. Only she won't be back from her border run until tomorrow.

Between the three of them, they have more than a decade of experience working full-time here at the park. And they're all gone.

Jessica's been tapped to act as tour guide, a role she first had to fill a few weeks ago when Jodi twisted her ankle. Because Jessica had already absorbed all of the elephants' stories, and because she could quite impressively already correctly identify every elephant at a glance, she was asked to serve as Jodi's replacement that day. She did so well that she's already spelled Jodi on half a dozen more occasions.

So the fact that she'll be leading the tour today is no biggie. More worrying is the fact that the two of us will be in charge of dealing with any unforseen problems that arise. We've already grilled Karl on what to do if, say, a few of the dogs get into a particularly nasty fight that leaves one of them horribly injured, or if one of the volunteers gets worryingly sick in the night. All of this is a daunting responsibility, but one that we're tremendously proud to have been entrusted with.

Jessica flashes me an encouraging smile. "We can handle this."

"Jumbo! Jumbo!"

It's Pom, yelling excitedly as she rushes from her truck up to the observation deck. She's in charge of most of the day-to-day operations here at the park, and serves as the de facto mother to pretty much all of the mahouts. Hidden beneather her gruff outer shell is a wondrously caring person. She's taken a bit of a liking to us because we're always willing to partake of the stir-fried insects she offers around from time to time.

She calls out a few commands in Thai, and then turns to me. I've never seen her so excited. "Jumbo, Jumbo!" she says again. "Jumbo leaving now. You and Jessica go pack!"

It takes me a second before I understand, and then suddenly I'm excited too. Lek's about to go on another Jumbo Express, a journey into a remote region of Thailand to rush to the aid of some suffering elephant in the middle of nowhere. Jessica and I never dreamed we'd be able to go on a 'Jumbo'...

Wait. Dammit.

"We can't go, Pom," I say sadly, shaking my head. "We're in charge of the park tonight. Jessica's leading the tour today and tomorrow. We can't go."

She nods in understanding, and then turns to Katie and Halley, two volunteers who have recently arrived at the park. "Ok, you two go. Go pack small bags. Bring passports, you might be go to Burma!" The two of them vanish in a cloud of excitement, off to pack up their things for the trip.

Choked with disappointment, but trying to be excited for Halley and Katie, I run off to tell Jessica the news. She gets as excited as I had, and then I see her face cloud as she realizes we can't go. Then her expression becomes determined.

"You have to go," she says firmly.

I shake my head, smiling. "I'm not going anywhere without you."

Since the day we set out on our trip (well, since quite a while before that, actually), we've only spent one night apart. When we first decided to stay long-term at the park, I flew down to Bangkok, grabbed the stuff we'd left in a locker there, and took the overnight train back. It was the only time in more than a year and a half that we'd been apart. And it was horrible. There's no way I'm going without her.

But suddenly she rushes past me, and by the time I catch up with her she's explaining to Pom that I'm going to be going too. Pom is smiling broadly at this, and telling me to go pack. My protests are falling on deaf ears.

"It's not fair that I go and not you." I can't go, I have to lead the tour. It wouldn't be fair for you to not go just because I can't. One of us should get to have this experience.

"I have to stay and help you with the park tonight." Don't worry about me, I'll be fine.

"Pom was saying there might be another Jumbo next week, we should wait for that one." I'll go on that one. You'll go on this one. The one next week might not actually happen.

"But..." If you don't go, we'll both regret it. C'mon, lets get you packed.

Seven of us sit around the table at the small restaurant in the Thai town of Mai Saliang. Next to Lek is Jeff, the longtime volunteer who works with her in the office and accompanies her on her Jumbos. Across from Jeff sits Chom, a cocky, charming Karen man who grew up working with elephants in a small jungle village, and has proven himself indispensible to Lek time and time again. In addition to Katie, Halley and myself, we're joined by a somewhat mysterious man named Boonchu. Chom came across Boonchu somewhere, and got him to agree to be our guide tomorrow. As a bonus, Boonchu says he knows a small village on the way where we can spend the night.

We've finished our food, a spectacular assortment of unidentifiable dishes of local Thai cuisine, and are now poring over the map that Lek has spread across the table.

"Right now, we here," she says, stabbing a finger at Mai Saliang. She traces her finger along the map as she continues. "Tonight, we go to here, and stay at village Boonchu tell us about. Then tomorrow morning we start early, maybe five o'clock, and we go to here. This the village where we go to see the elephant. Very hard road, I think."

Her finger is resting directly on the border between Burma and Thailand. Generally speaking, traveling to Burma involves getting a visa well ahead of time and flying in to Rangoon or Mandalay. Other than as a little day visit to a bordertown, you're not allowed to cross into Burma at a land border. The country's in the midst of a four-decade-old civil war, and tourists aren't allowed to visit the places where the government is waging genocide on its own people. Places like the bit of the map where her finger is resting.

She lifts her finger, and peers at the map in thought. Now visible, previously obscured by her hand, is text that reads "sensitive border area." The table erupts into a bit of nervous laughter.

Katie wonders aloud whether "sensitive" means the border is being challenged in the courts. Jeff shakes his head. "It means," he replies, "that it's being challenged on a grassroots level with guns and landmines."

A brief silence falls over the table. Everybody looks over at Lek, who shrugs.

"I don't know," she says, "if we come back, or if we not come back."

The girls look shocked. Jeff is coughing in surprise. "You mean you think we might not survive this trip?" I ask.

Lek blinks at me in surprise, and then erupts into laughter. "No, I mean maybe we come back tomorrow night, maybe not until Saturday."

We stop for the night in a small Karen village, and walk together up to the traditional stilt-house where Boonchu wants to arrange for us to stay the night. Inside we are all introduced to the man who lives there, and he quickly agrees to put us up: in exchange, Lek and Chom will prepare breakfast tomorrow morning from supplies we bought in Mai Saliang.

Later, the seven of us are sitting around with our host, whom I will refer to only as "Mr. X" (for reasons which will become clear later). As is their habit, Lek and Jeff have steered the small talk towards the subject of elephants, with the intention of gathering a little statistical information. They're speaking with Mr. X in Thai, and translating his responses into English for the benefit of Katie, Halley, and me.

When asked how many elephants live in and around the village, he gives an answer that immediately catches their attention. "There used to be more than a hundred here," he says, reminiscing about the good old days, "but now there are only six. They never stay here for more than a few months at a time... elephants are always just passing through."

Jeff explains to us, quietly, that we've all stumbled onto a village where elephants are illegally smuggled into Thailand from Burma, given fake papers making them out to be Thai elephants, and then sold on to elephant camps and circuses. It's something Lek has been trying to raise awareness of for a long time, and suddenly we're all unwittingly sitting in the heart of it.

In the conversation that follows, several amazing things unfold. Among them are the revelation that Mr. X is himself an elephant smuggler, and that he's willing to go on the record. Tomorrow morning, when the light is better, Lek will videotape an interview with him in which he will talk openly about how he smuggles elephants in from Burma. It's a huge breakthrough for her.

We all retire to "bed", sleeping on mats on the floor. Katie and Halley sleep in the small sideroom, while Jeff and Lek and I sleep out in the main room. There is so much new information swirling around in my head that I don't get much sleep at all.

Jeff is already up and about when I open my eyes. And he's worried.

The cause of his discomfort is immediately apparent. Just outside Mr. X's front gate, a small crowd of angry-looking men has gathered.

"They're other smugglers from the village," Jeff says, in answer to my unspoken question. "They don't want Mr. X to give this interview. But because he's doing it in his own house, they can't really stop him."

There are probably a dozen or so men out there, all grumbling to one another and fixedly staring up at the house. Several of them are glaring at Jeff and me. I repress a shiver.

"Uh, Jeff, are we in any danger here?"

Jeff shrugs, that worried look still on his face. "From what I understand, Chom's trying to trick them into thinking that we're just looking to buy an elephant or something. So we should be ok."

"Uh-huh."

In the end, it works out pretty well. Lek gets her interview, and the smugglers are duped into believing that we're there as buyers. They take us around to the different places where the elephants are hidden, to see if we want to buy any of them. Lek and Jeff pump them for information while Chom videotapes everything and I take pictures. Lek makes arrangements to return to the village to meet with Mr. X again.

And then it's time to go. We still have to travel on to our "sensitive border area", and meet with a very special elephant.

"I hear about this elephant a long time ago," Lek tells me as we drive. "She Thai elephant, not Burma. I hear about her, and her story make me very sad. I look and look for her, but can never find. And now I hear that she is here, that I can come and see her. I think I will try to buy her, to bring her to the park."

I ask her what it is about this elephant that is so sad, that she's been looking for her for so long.

"When we find her," she says, "I think you will understand."