Chris forged ahead, once again charging through the forest like a maniac, his machete flashing. All the machetes we carried had strips of Day-Glo pink tape on their blades, so they could be seen and avoided. The vegetation was so thick that it was easy to see how someone could get sliced open by a machete-wielding neighbor, and even with the Day-Glo tape there were a couple of close calls. Woody, Juan Carlos, and I tried to keep up with Chris. Beyond the ravine, we explored a second plaza, twice as large as the first, also delineated by mounds, berms, and raised earthwork platforms. On the far side, too, were two low, parallel mounds with a flat area in between, which Fisher mapped out with his GPS. He believed it might have been a Mesoamerican ball court, having a similar geometry and size. This was especially interesting, as it indicated a possible link between this culture and its powerful Maya neighbors to the west and north. Far more than the casual recreation we think of when it comes to games of skill, in Mesoamerican cultures the ball game was a sacred ritual that reenacted the struggle between the forces of good and evil. It might also have been a way for groups to avoid warfare by solving conflicts through a match instead, one that occasionally ended with human sacrifice, including the decapitation of the losing team or its captain.

I followed Chris and Juan Carlos around as they hacked this way and that through the jungle, surveying and mapping the plaza. I was especially intrigued to see the famous “bus” mound, which was so striking on the lidar images. In reality it was a perplexing earthen construction, with a sharply defined base and steep walls.

“What the heck is it?” I asked Chris, as he poked around it, marking way points on his GPS.

“I think it’s the foundation of a raised public building or temple,” he said, explaining it was situated at the far end of what had once been a big plaza, where it would have been prominently visible. “There was something on top that’s gone now, built out of perishable materials.”

The rain ceased, but the trees continued shedding millions of drops. The light filtered down, cloudy green, as though passing through pond water. I stood breathing in the rich odor of life, marveling at the silent mounds, the immense trees choked by strangler figs, the mats of hanging vines, the cries of birds and animals, the flowers nodding under the burden of water. The connection to the present world dissolved, and I felt we had somehow passed into a realm beyond time and space.

Soon enough, the peace was broken by another downpour. We continued exploring. It was exhausting, soaking work, pushing through the jungle, unable to see where we were putting our feet, the ground as slippery as ice. We climbed up and down steep ravines and hillsides, made treacherous by mud. I learned the hard way not to grab hold of a stick of bamboo, because it would sometimes shatter into sharp, cutting pieces and dump on me a load of rank water that had accumulated in its hollow stem. Other potential handholds sported vicious thorns or swarms of venomous red ants. Downpour after downpour came and went, like someone turning a tap on and off. Around one o’clock, Woody became concerned that the river might be rising, preventing our ability to cross back to camp, so we returned to where Anna, Alicia, and Tom were working on the row of stones. As they cleared the area, they had discovered, in the corner of the plaza, a stone staircase that went down into the earth, partially buried by slumping mounds. We paused in the rain while Woody passed around a thermos of hot, sweet, milky tea. Everyone was talking excitedly. Even with the minimal amount of clearing, I had a better feeling for what this tiny corner of the city was like, with its row of stones propped upon boulders. They certainly looked like altars, but were they places of sacrifice, or seats for important people, or some other thing? And the stone staircase that went nowhere was another puzzle. Where did it go down to—some underground tomb or chamber? Or did it lead up to something that had washed away?

Too soon we had to leave. We set off in single file, back to camp, again skirting the base of the pyramid. It was a route we had taken several times before without noticing anything special. But suddenly Lucian Read, in the back of the line, called out, “Hey! Some weird stones over here!”

We returned to look, and all mayhem broke out.

In a broad hollow area, just poking out of the ground, were the tops of dozens of extraordinary carved stone sculptures. The objects, glimpsed among leaves and vines, and carpeted with moss, took shape in the forest twilight. The first thing I saw was the snarling head of a jaguar sticking out of the forest floor, then the rim of a vessel decorated with a vulture’s head and more large stone jars carved with snakes; next to them was a cluster of objects that looked like thrones or tables, some with carvings along the rims and legs that, at first glance, appeared to be inscriptions or glyphs. They were all almost entirely buried, with only the tops visible, like stone icebergs. I was astounded. These sculptures were in beautiful condition and had probably been lying here undisturbed since they had been left centuries ago—until we stumbled across them. This was proof, if we needed it, that this valley had not been explored in modern times.

The crew crowded into the area, jostling each other and exclaiming in astonishment. The camera team was shooting and Dave Yoder was in there, too, photographing like a madman, while I also had my Nikon out, taking pictures in the rain. Chris, the archaeologist, began yelling for everyone to get back, dammit, don’t touch anything, quit stomping around, watch your feet for chrissakes! Cursing and driving people out, he finally roped off the area with Spanish crime-scene tape that spelled out CUIDADO, “warning,” which he had been carrying (with remarkable foresight) in his backpack.