Perusina, Perusino, and Franz in the Cordillera Escalera

Franz stopped so suddenly that Perusino stumbled against his bushy tail.

"Hey! Your rear brake just activated!"

Franz didn't answer. His nose twitched. Once. Twice. Then he perked up his ears.

Perusina first heard only the waterfall. Ahuashiyacu thundered over the rocks behind them, white and loud, as if the mountain itself were speaking. Water dripped everywhere. From leaves, from lianas, from moss. The Cordillera Escalera was not a normal forest. It was a giant green staircase: step after step, slope after slope, mist upon mist.

"Smoke," Franz whispered.

Perusino grinned. "Maybe someone's grilling bananas."

Franz slowly turned to him. "That's not barbecue smoke."

Then there was a crack above the path. Perusina raised her hand. Another crack. Then small stones slid down the slope. One bounced against Perusino's shoe.

"Someone's up there," Perusina said.

They climbed off the path. The ground was slippery, roots ran like snakes over the slope, and the mist made everything seem both closer and farther away at the same time. Franz led the way, his nose close to the ground. Suddenly he sneezed so violently that he tumbled backward into a fern.

"Very mysterious," Perusino said. "The famous tracking fox falls into salad."

"Shhh!" Perusina pointed to a tree.

A red mark was cut into the bark. Not old. Fresh. Beyond it, another. And another.

"Markings," Perusina said. "Something is meant to be cut here."

Perusino became serious. "But this is a protected forest."

Then they heard it: a thin, hissing sound.

Franz shot off.

"Franz! Wait!"

Too late. The little Sechuran fox disappeared among the leaves. Perusina and Perusino ran after him. Branches slapped their faces. Mud splashed. A liana hung across the path. Perusino tried to duck under it, got his backpack caught, and suddenly dangled halfway in the air.

"I've got the situation under control!" he shouted.

"You're hanging from a plant!" Perusina shouted back.

She pulled him free. Together they crashed through some bushes and suddenly stood before a clearing.

There lay dry undergrowth. Far too neat. Next to it stood three young trees, half-sawn. And at the edge, a wisp of smoke crawled from a pile of palm leaves.

Franz pawed at the ground. "Something's smoldering!"

Perusina ripped off her scarf and beat at the smoking leaves. Perusino ran to the small stream that was supposed to cascade over stones next to the clearing. But the stream was only a thin trickle.

"It hardly carries any water!"

Then something whistled.

Not like a human. Not like a bird.

A short, bright sound from the moss.

Perusina knelt. Between two wet leaves sat a tiny frog. Green-brown, barely larger than her thumb, with eyes like two black pearls. It whistled again. Then it jumped away. Not into the forest. But uphill.

"It's showing us something," Perusina said.

"Or it has appointments," Perusino mumbled.

The frog kept jumping. The three followed. The smoke grew stronger. Then they saw the reason: Above the clearing, someone had blocked a narrow ditch with branches. Water was dammed behind leaves and mud. The stream below received almost nothing. And right next to the dry streambed, more leaves glowed.

"If the fire goes up the slope..." Perusina began.

"...the whole dry swathe will burn," Perusino said.

At that moment, a piece of earth broke away.

Perusino slipped.

He slid down the slope, taking some ferns with him, turned once around himself, and at the last moment, held onto a root. Below him lay sharp stones.

"Everything's fine!" he shouted in a very high voice. "Only my heart briefly fell out of my backpack!"

Perusina jumped to him, lay flat on her stomach, and stretched out her hand. Franz bit Perusino's sleeve and pulled too. Inch by inch, Perusino crawled up.

Then the root cracked.

Perusina gripped tighter. Franz dug all four paws into the mud. With a final jerk, Perusino was back up. His face was brown with mud, only his eyes were still round.

"I'm for it," he panted, "that from now on we do adventures sitting down."

But there was no time for that. The smoke below grew darker.

Perusina grabbed a thick branch. "We have to open the blockage."

Perusino nodded. Together they pried branches from the ditch. Franz dug with his paws in the mud until dirt stuck to his ears. At first, nothing moved.

Then it gurgled.

A small gush of water shot through the gap.

"More!" Perusina called.

They pulled, pushed, kicked, dug. Suddenly the whole plug broke. Water rushed down the slope, leaped over stones, hit the dry streambed, and raced to the clearing.

Below, it hissed loudly.

Steam rose.

The smoldering died out.

For a moment, no one said anything. Only the waterfall thundered in the distance. And somewhere in the moss, the little frog whistled again.

Franz shook himself. Mud flew in all directions. A clump landed on Perusino's nose.

"Thanks," Perusino said dryly. "Now I look like a very disappointed cocoa biscuit."

Perusina laughed, but then she saw the red marks on the trees. "We need to get the park rangers."

On the way back, she marked each tree with small stone arrows on the ground. Perusino took photos of the cuts. Franz sniffed the human trail to an old tarpaulin, under which lay a rusty saw.

When they returned later with the rangers, the smoke was gone. The stream flowed again. The tiny frog sat on a leaf and whistled, as if he had orchestrated the whole thing.

Perusina looked up into the cloud forest. "The Cordillera Escalera really is a staircase."

"A rather slippery one," Perusino said.

Franz lifted his nose. "And now it smells right again."

"Like forest?" Perusina asked.

Franz nodded.

Perusino sniffed. "I only smell mud."

Franz grinned. "Then it suits you."