We were all in love with this thing – me, Gabi and Sol. Something about its creaky movements and its accidental smile was so endearing. To us this happy little sucker was as glad of our attentions as we were to give them.

Yes, it was kind of gross too, this sloth. It was the rainy season. Algae had blossomed on its thick fur in such quantities that our hands were covered in the stuff. The animal was lighter than you would imagine and weak for its size. It put up little resistance as we strapped on the harness, driving several dozen moths from its shaggy recesses. These pale insects stumbled drunkenly over our mosquito bites.

‘I found a sloth skeleton once,’ Sol said. ‘It was still hanging in the tree. It must have died up there, with its wrists locked around the branch, and just hung about while its bones were picked clean.’ One of the moths was so thirsty for the sweat on Sol’s cheek that it did not flee when he wiped his hand across his face, disintegrating the insect across the dark field of his stubble.

‘This is the first I’ve ever seen,’ Gabi said. The sloth’s grin was infectious, and Gabi couldn’t stop staring at its face and giggling. The creature had its long arms around her neck, its shag-pile belly staining her shirt green. She held it close to her body while I clipped the monitor strap around its neck.

‘It’s my first, too,’ I said. ‘It smells funky.’ Gabi bent her head closer to its neck and took a sniff.

‘It just smells like the forest,’ she said. And I guess that was it exactly. This dopey tree-hugger was a living manifestation of the rainforest, of the thick mulch on which we had been walking for days, of toadstools and rancid- smelling orchids, gibbons and cicadas – the whole sweaty playground.

The first blast of helium that Sol pumped into the balloon startled a thousand things. Brittle feet scratched across table-top leaves, paws thumped an erratic heartbeat across the forest floor. High above, in thecanopy, a hornbill quitted its perch, the terrific swooshing of its wings prehistoric. But the sloth showed none of this alarm, only swaying slightly in Gabi’s arms.

‘There, there, little one,’ she whispered. ‘It’s okay.’ Sol turned the release valve again, huffing life into the great white lung. ‘Are you using the biggest one?’ I asked. ‘Uh huh.’

‘This thing’s much lighter than it looks,’ I said, stroking the top of the sloth’s head. ‘We don’t want it to go too fast.’ The sloth was now exploring Gabi’s neck with its short snout, and she was giggling.

‘The next size down is a forty-litre,’ Sol said. ‘It won’t be big enough. I’ll just fill this one about eighty percent.’

The balloon was now taller than Sol. He held its narrow throat in one hand and, even with his arm fully extended, the side of it pushed against his face.

‘Let me help with that,’ I said. I took the balloon from him and he turned the helium canister valve to slow the inflation, watching the pressure needle climb.

‘You’re bleeding again.’ I pointed at the bandage wrapped around Sol’s hand. Two days ago a tamarin we had been working on had bitten him, its little teeth puncturing the soft flesh between thumb and forefinger. The bandage was bunched up in this valley and bright with fresh blood.

‘I’ve changed it twice already,’ he said. ‘Damn thing won’t stop.’

‘Maybe we should go back to camp today instead,’ Gabi said. ‘You might need that thumb in the future.’

Sol shook his head.

Gabi took the sloth’s arms from around her neck and sat the thing in her lap. It seemed quite happy to be there.

‘Done,’ Sol said. I held the throat of the balloon while Sol closed it off with a steel clamp and then screwed in the threaded end of the wire. Fresh raindrops pattered on the balloon’s surface.

‘You sure this is inflated enough?’ Sol asked.

‘It’s lighter than you’d think,’ I said.

From the case in my bag I unpacked one of the explosive bolts and, after blowing moss and dirt out of the screw hole on the harness, twisted it into place. Gabi brushed a moth from the back of my hand, and I gave her a covert wink.

Sol hooked the karabiner at the end of the balloon wire to the loop of the explosive bolt and gave it a gentle tug. Gabi and I tested all the buckles of the harness, making sure they were secure, and that the sloth’s fur was not caught anywhere.

Sol released the balloon and I pinched the wire between my fingers, slowly releasing it so the sloth didn’t experience a sudden jolt. Gabi and I held the sloth together, our fingers meeting here and there, concealed in amongst the thick green fleece. Sol was not watching but unpacking the laptop.

‘You’re gonna have to let it go at some point,’ he said.

‘Ready?’ I said. Gabi nodded.

Gently, we allowed the lift of the balloon to take the weight of the sloth, which looked like a baby in a bouncer, still grinning, its legs dangling. Gabi maintained a cautious grip on one foot as it rose, and then let it slip from her grasp. The sloth reached up with one arm and hooked its claws around the wire. We watched it ascend all the way through the understorey, our open mouths catching raindrops. The sloth did not wiggle or thrash about the way most things do but acquiesced to the demands of the balloon, following the vines up into the canopy, until it was just a green dot beneath the balloon, a pupil in the great eye gazing back at us. Here the canopy was sparse, great holes rent into it by illegal loggers, but these gaps allowed the balloon an easy passage that would be impossible in the pristine areas.

‘It’s all coming through,’ Sol said. ‘The speed is just right. The data is spot on.’

‘Straight as an arrow,’ Gabi said, gazing skywards.

The keys of our laptop were sticky with the juice of citrus fruits, the screen a maze of fingerprints where we had pointed things out to each other on previous lifts. Direct feeds from the monitors poured in, a line of seven digit numbers from the altimeter cascading down the screen at a rate of ten data points per second. In a separate window, the monitor around the sloth’s neck relayed the creature’s heart rate and blood pressure, which were translated here into green waves on a graph.

‘Cool as a cucumber,’ Sol said. ‘I think our little friend is going to be the highest yet.’

All around us fatter raindrops hit leaves. Gabi wiped the back of her neck.

‘Do you want your poncho?’ I asked.

‘I’m fine,’ she said.

Sol did not break his gaze from the laptop screen but turned his head towards me a little.

‘Well, he’s joined the mile-high club now,’ I said.

‘Do you think it was a he?’ Gabi asked. ‘I thought it was a girl.’

‘It was a male,’ Sol said.

‘Did you see his little sloth balls?’ I said.

Sol reached round to touch the middle of his back. ‘The patch between its shoulder blades,’ he said.

‘He’s really going for it,’ I said. ‘He’ll be a record-breaker in a second or two … there!’

We all cheered, clapping our hands above our heads. I rubbed the palm of my hand on Gabi’s back. She reached her hand out to squeeze my arm but her timing was off and there was an untidy collision of limbs as I retrieved my arm.

‘How high do you think he’ll go?’ I said. ‘We’re going to have a hell of a hike to find him afterwards,’ Gabi said. ‘Seriously?’ Sol said, looking round at her.

‘What?’ She said. ‘You weren’t thinking about leaving him?’

‘Well, not until it went this high. It’s still going. It could easily drift into the valley now, get caught up in a tree.’

‘This little feller could be the one that unlocks everything,’ I said, swooping my hand up in a steeply accelerating curve, fingertips for nose cone, folded thumb for wing. ‘We owe it to him.’

‘It’s already two-thirty,’ Sol said. ‘We’re unlikely to find it now before nightfall.’

‘We weren’t going back to camp tonight anyway,’ I said.

‘But it could take us way off course. I’m not going into one of the dodgy areas for the sake of one sloth.’

‘We’re going to get him,’ Gabi said. ‘And that’s that.’ ‘That’s that, is it?’ Sol laughed. ‘Come on, don’t be like that,’ I said. On the screen the data was still flooding in.

‘I hope the monitor’s not screwed,’ Sol said. ‘It’s over twenty-one hundred now.’

‘No, the readings are good,’ I said. ‘You wait, any moment now he’s going to go.’

We all stared at the screen, the raindrops beating a faster, heavier rhythm now against our backs. Sol pulled his poncho from his backpack and made a canopy for the laptop.

‘It’s too high,’ he said. ‘Give it a moment longer.’

‘Come on little one,’ Gabi said. She showed me that her fingers were crossed and I gave her an appreciative smile.

And then suddenly the sloth’s blood pressure rocketed, and the characteristic spike and sudden drop off indicated that it had reached its ascension threshold and been rendered unconscious.

‘There!’ I said. ‘You beauty!’ I punched Sol on the arm.

The sloth was so high that the sharp crack of the bolt exploding, jettisoning the balloon, was inaudible this time. So, too, the snap and whoosh of the parachute deploying. We all stared up into the bruising sky, our hands shielding our eyes against the rain, looking for the bright orange segment of the parachute, but even after two minutes it didn’t appear.

‘It’s gone way off,’ Sol said.

Gabi lifted the GPS tracker on her belt and thumbed the rubber power button. I began to pack our things. Sol clapped the laptop shut and stuffed it into his pack.

‘He’s still drifting,’ Gabi said. ‘But it’s not more than a couple of miles.’ ‘Yes, but a couple of miles here?’ Sol said.

‘Honey,’ Gabi said, putting both her hands on his shoulders. ‘We really have to. Please?’

Sol held her gaze for a moment, then, rolling his eyes, said, ‘Fine. But if we hear even the faintest hum of a chainsaw or smell a whiff of smoke, we’re turning around. Deal?’

‘Deal,’ she said, smiling, then closed her arms around his neck and kissed him on the mouth. She made a noise of disgust and released him. ‘You’re dripping,’ she said. ‘Are you feeling okay?’

‘I’m allowed to sweat in the jungle.’

It was my turn to carry the heavy pack – the one that held the helium canister. I passed it to Sol and he lifted it so I could loop my arms through the straps.

‘Which direction?’ I said.

*******

The GPS co-ordinates settled, indicating that the sloth had touched down 3.2 miles away. Gabi wiped raindrops from the backlit screen. We were one green dot, and the sloth another, just a few centimetres apart.

Across this space we progressed a pixel at a time, Sol in the lead, slashing leaves with a machete and throwing sticks through vast webs. We had to climb across fallen trees, leap over processions of army ants and, at one point, wade through a slow-moving river that was so deep we had to hold our packs above our heads while rain splashed up into our faces. When we got to the other side we undid our belts and stripped down to our underwear to check for leeches. I risked a glimpse at Gabi’s wet legs, and when she snapped the elastic of her knickers back against her skin, I felt it as a pulse inside my belly.

*******

The sky gradually turned flame orange. Sol stopped and turned around.

‘We should set up camp,’ he said. He was panting. For the last hour his pace had been slowing.

‘You look like crap,’ I said.

Gabi put her palm to his forehead.

‘You’re freezing,’ she said.

‘Just stop it,’ he said. ‘This looks like a good place to rest.’

‘But we can’t leave the sloth in the harness all night,’ Gabi said.

‘We’re never going to reach it before dark,’ Sol said.

‘How much further is it?’ I asked.

‘Just over a mile,’ Gabi said.

‘That’s another couple of hours!’ Sol said, wrinkling his face in pain.

‘We can make that,’ Gabi said.

‘Look,’ I said. ‘Sol, you’re wasted. You rest here, start setting up the camp. Gabi and I can hot-foot it and be there and back in no time.’

Gabi nodded, her hands on her hips.

‘No way,’ Sol said, shaking his head. ‘We’re not splitting up. It’s much further than you think, and we’re getting way too close to Etuya. We’ll rest

now, and then head out at dawn. The weather’s setting in too.’

Gabi covered the sides of her face with her hands and looked at me. I chewed my lip.

‘I think Gabi and I should go,’ I said. ‘We can stay in radio contact. And if the rain gets bad and we can’t make it back, we can always set up camp and meet you back here in the morning.’

Sol glared at me. ‘Fine,’ he said, picking up his pack. ‘We’ll all go.’

‘You’re not well,’ I said. ‘You need to rest. And to be honest, mate, you’ll only slow us down.’

Sol looked at Gabi. ‘We’re not splitting up,’ he said.

She stroked his arm, and said to me, ‘Why don’t you take Sol’s pack, and we can leave the big pack here, then come back for it in the morning?’

‘Sure,’ I said.

‘Fine,’ Sol said, throwing his pack at my chest and wiping his face with his sleeve.

*******

We were less than half a mile from the sloth when Sol tripped over a root and fell for the third time.

‘You should have stayed,’ I said.

‘It’s too dark to see a damn thing,’ Sol said.

‘What do you reckon?’ I asked Gabi.

She sighed and tucked the hair that had spilled from her ponytail behind her ear.

‘We’ll have to stop.’ At night we all slept in one tent alongside each other, Sol, then Gabi, then me. Sol grumbled in his sleep. I lay on my side, facing Gabi. Often, the soft patter of raindrops on the tarpaulin above my head was accompanied by the percussion of larger things striking the surface. Mostly these sounds were small and sharp, the clear tap of a beetle’s back. Sometimes the thump was heavier, a sound that made me visualise hairy abdomens and a multitude of legs. The silence that followed these heavier thumps was worse than the thumps themselves.

I moved my hand with excruciating slowness out of my sleeping bag, listening all the while for a break in Sol’s sleep noises. Reaching across, I placed the back of my hand against the side of Gabi’s sleeping bag. I was hungry for her solidity and, finding it, was comforted.

My hand had been there, curled against her side, for no more than a minute when I felt her fingertips in my palm, spreading my fingers wide, laying her hand down flat upon mine, locking together at the knuckles, and squeezing.

*******

Gabi got us up and moving while the sky was still a dark slate. We ate on the way, swallowing down cereal bars with warm water from our flasks. Sol could eat nothing but painkillers, but Gabi would allow him no rest.

‘The sloth’s been out there tangled up all night,’ she said. ‘He’ll be starving.’

Gabi took the lead, and the machete, setting a relentless pace that Sol struggled to maintain. After an hour or so, she spotted the bright orange nylon of the parachute and broke into a run. I kept with her, leaving Sol in our wake. And it was together that we burst into the little clearing, scaring the thing away, whatever it was – a jaguar, I think, from the brief flash of its hind quarters and tail that we saw as it leapt out from beneath the chute and disappeared into the forest.

Here we stopped.

Gabi uttered a small sound of remorse. In those seconds that we were alone, I put my arms around her, turned her towards me and squeezed her tight against my chest. I peered down at her face. There were no tears, but

redness and anger.

‘We should have come last night,’ she said. ‘We shouldn’t have stopped.’

This is how Sol came upon us, pressed close together, behind us the bloodied parachute. He hung his head and, in squatting down, lost his balance and fell onto his knees.