AFTER A THREE-HOUR American Airlines flight to Medellín, I board a turboprop commuter plane that takes me over 7,000-foot mountains rising between Medellín and Cali. By the afternoon of my second travel day, I'm sitting with Kelvin—a six-foot-tall man of doughy bulk, pale skin, and button eyes—on the patio at the Iguana Hostel, enjoying the botanical exuberance of aloe, orchid, mango, and passionflower, all growing virtually untended.

In person, Kelvin has an incongruous timidity about him. His eyes never meet mine, and he's sulking because he wanted to press on toward the coast this very afternoon. But I need downtime. He nags that we should take off at 4:30 a.m. No: I also need fun time, and I don't want to wake up drunk. Kelvin looks at his sneakers; our "road buddy" dynamic is off to a bad start.

The fun quotient increases when Paula shows up out of the blue. A quick-witted, cappuccino-skinned 28-year-old, Paula is on her way home from her job as a secretary and stops in to see a friend who manages the Iguana. She sees us sitting there drinking and decides to join us. (What a country!)

"El Valle es peligroso?" I ask, genuinely interested in how dangerous the town is or isn't. I'd noticed that only one of the past 1,500 entries in the hostel's logbook lists anything in that direction as the next destination.

"No, all of Colombia is safe," she says. "Except me."

Before long, Paula insists that Kelvin, I, and a Parisian photographer named Jean-Paul Loyer go dancing with her at Salamandra, a monstrous neon salsoteca just off Avenida 6N. But Kelvin doesn't want to. He has a girlfriend back at the Black Sheep, and he's miffed that he's taken time off from his hostel only to end up in another hostel. He'd rather lay his big body in the hammock with a beer. Or 12. His idea of fun is self-lubrication—and logging on to PokerStars.com as the much feared "Kiwipaisa."

We leave the club at 2 a.m. on April 12. Unknown to us, at that exact hour, heavy rains have started triggering mudslides on the highway from Cali to Buenaventura, our road to the Pacific coast. Before the rains stop, the slides will devastate much of the province of Valle del Cauca. By early that morning, swollen tributaries of the Dagua River have started 17 mudslides, closing 13 miles of the highway and wiping out two villages. Thirty-three people die, mostly families caught in their homes. Thirty more are injured. Three hundred are left homeless, to be evacuated by government helicopters to a nearby sports stadium. A few days later, Colombia's president, Álvaro Uribe, will helicopter in to declare a state of emergency.

Upon hearing the dark rumors circulating around the spotty news coverage, Kelvin gets pissed that I delayed us. "If we'd left at 4:30 like I wanted to, we'd be there by now," he says at dinner the third night.

"No," I fire back. "If it weren't for me, we'd be dead under the dirt."

It turns out we're both wrong—the road was impassable even at 4:30—but my comment has the desired effect: Kelvin leaves for the bathroom. When he returns, I politely tell him to get off my back. "Listen, Kelvin. I'm still excited to go, but you're not obliged to do this."

"No," he says, setting down his beer. "We're going, and we're going to bed tonight at midnight."

Cheers.