“Well...This is as far in as she’ll take us.”
(This might be a good place to place a descriptive chapter about where the characters are and begin 'setting the scene.' The earlier you start 'setting the scene' the better.)
With a huff, the driver exited the truck, kicking a dent into the rusted exterior. He took a moment to calm himself down <(this word feels redundant), running a hand through his long, blonde hair, and patted the truck’s faded paint. He <(You already started the previous sentence with this word) looked back and forth for any creatures preying about the road <(Finish the sentence here) for something to eat. When <(Redundant word) his gaze only <(Redundant word) found broken and scrapped cars abandoned years earlier, he reached into the truck’s back and shook his sleeping passenger awake.<(If he's shaking a sleeping passenger then of course they'll wake. Trust your audience to know this so you don't have to add an extra redundant word.)
“Rise and shine, doc,” he chuckled. “This hunk o’ junk is going nowhere.”
The young man yawned and stretched himself out, scratching at his raven hair <(Watch out for cliches like black hair being described as "raven.") that stuck up in all directions from his nap. Hopping onto the decrepit <(using adjectives like this should be reserved for times when you want to be impactful. Be mindful not to overuse them or they won't work when you really need them.) road, he strolled over to the side, where the lady in the passenger seat struggled to push open the protesting <(using this word implies the door has some sort of agency, which is doesn't. Rethink whether you need the word "protesting" in this instance.) door.
“Is it stuck?” He asked, examining the edge of the door.
“The stupid thing is--” She kicked the handle with a thud. “--rusted from the inside. Isaiah, could you please get Sam to open this?”
Isaiah crossed his arms, glancing across to the driver on the other side of the vehicle.
“Well...why can’t I open it?”
“You wanna try?” She laughed, sitting back into the passenger’s seat. <(We know she's in the passenger seat. So there's no need for the extra detail. Perhaps just write "sitting back.") “Alright. Sure. Be my guest.”
Isaiah rubbed his gloved hands together. Focused <("Focusing"?) , he gripped the handle of the door and pulled back with all his might. He held his breath, shutting his eyes tightly as if to will more strength into himself. Despite his effort, the door remained shut and Isaiah hung his head and sighed. Begrudgingly, he walked over to the taller, stronger man standing by the truck and gestured to the door.
“Could you give my colleague a hand, Mr. Dale?” He mumbled.
“With pleasure,” The man said with a nod, making his way over to the other side of the truck. He took the handle in one hand and, with a tug, sent the door flying open.
The woman stepped back down onto the road and gave a satisfied nod to Samson. She proceeded ahead of the group to an ancient road sign that had toppled over years ago. Vines twisted their way up the sign until the words could no longer be seen underneath their leaves. Carefully, she clambered up the sign’s pole, which creaked and groaned under the tiniest amount of pressure. From the top, she had a view of the city and the massive structures that nature had overtaken. Some of the tallest pillars peaked their heads out of the plants that swallowed the shorter buildings whole.
“Whaddaya see, Rachel?” Called Samson.
“The road is good,” She replied from her perch. “Not too many obstructions. It should be a safe path into Kanahn.”
“I hope your research is worth it, doc,” Samson said to the smaller man. “The council spent a lot of resources to prep this trip into an Afflicted Zone.”
Isaiah nodded his head. Months of debating, researching, and writing essays had brought him to this moment. It was a daunting task to convince the Central tribes to fund his research into the ancient city. Finding volunteers to enter into the Afflicted Zone was even more difficult a task. Of the very little knowledge retained from the ancient world, the most complete understanding was of the Affliction’s devastating effects on the nervous system. Death would be certain without protective gear. <(There's too much 'telling' in this paragraph it feels like a mini-info-dump).
“For their assistance, I’m thankful.” Isaiah checked a PDA strapped to his wrist, which made a steady tone when pointed towards Kanahn. “But I assure you, their money will not go to waste. So long as you don’t break my equipment.”
“Those buckets you call helmets?” Samson guffawed with such force that Rachel nearly stumbled off of the sign in surprise.
“Yes, the ‘buckets’ with the air filters. To save your life, Mr. Dale.” Isaiah said. A moment later, he mumbled under his breath. “If all your hair will fit underneath, that is.”
“You know how he feels about his hair,” Rachel called, descending from the sign. “His people would eat you alive for your comment. So how about you two compose yourselves so we can do our job and leave, please.”
Samson patted Isaiah on the shoulder and proceeded forward down the road, behind Rachel. Isaiah trudged behind in silence, keeping his eyes trained onto <(eyes are usually trained "on" something not "onto") his PDA. He glanced up to Kanahn as they creeped <("crept") towards the derelict city. He knew they were prepared. Every single factor was accounted for in his equipment. Their journey would be quick and seamless. And yet, he could not rid himself of the growing fear that seemed to emanate from the heart of the city itself.
This is nicely done. Though there is very little setting of the scene in the opening paragraphs you seem to correct this by the end and I could clearly picture where they were. This story definitely intrigues me however you didn't do much in the way of describing what any of the characters looked like except perhaps one. Detail and description and equally as important as dialogue and action, try to balance them. I hope you keep writing, this seems like it could be a great story.