The twilight shadow loomed over the land, a crescent moon hanging high in the sky. The city underneath it, Maribor, was split into two halves. One sat within the towering walls, where beautiful buildings stood. They were brightly lit, and merry noises came from the taverns. Soldiers patroled the streets. The other half slumbered beyond the city walls. The houses were in ruins, and the ground was cracked. Weed slithered across the earth. Refuse and rancid beds left by beggars and tramps were strewn across the place. Horrifying craters haphazardly covered the land. These were left by meteor strikes.

Howls of wolves and rabid dogs came from the dark corners of this abandoned land, while bugs chirped among the bushes and scarce trees. A ravine measuring more than a hundred yards long crushed the old city wing. Not even the moon could shine on any of its crevices. It was like a titanic python quietly hiding in the darkness.

Dark silhouettes hopped along the ravine, dropping silently like gazelles leaping through a valley. Their cloaks absorbed all the silvery moonlight, keeping them shrouded in darkness. Like phantoms, the silhouettes disappeared in a moment.

A patch of crimson roses stood in the southwest of the crack. There, the silhouettes found a dark entrance.

"Sewer number thirteen in the old city wing." Roy and his comrades exchanged a glance. They quickly cast their Signs, covering themselves in magical barriers of gold and black. The monster hunters downed their supply of Cats, and their pupils expanded. They saw through the night easily, as if they were traveling in broad daylight.

Roy walked down the rickety wooden stairs, and the steps creaked as he went. A couple of moments later, the young witcher landed safely. His silver eyes glowed in the dark, shining on a dark and ancient passage. There were craters on the walls flanking them. Weed and ivy slithered over their surface, while wet moss was draped over them.

The old city wing was abandoned for many years, but the sewers were connected to Maribor's. The city's refuse and sewage flowed into these tunnels every day. The dark and humid tunnels kept everything cooped up, and now even the air was filled with a foul odor.

***

The tunnel was split into different paths, all leading into the unknown darkness. Smell of rotting, festering refuse filled the air. A black, gooey river flowed in the ditch sitting in the center of the tunnel. Garbage, rotting leftovers, excrements, and a myriad of items flowed through it. The witchers saw boots, tattered clothes, and bones of small animals floating around.

A reluctant Kiyan was assigned to guard duty by Triss. He stood by the sewer's entryway, just in case anything unpredictable were to happen. Eleven witchers along with Coral and Kalkstein, traveled both sides of the passage, their footsteps careful and soft. They tried their best to stay silent.

Like a cat on the hunt, Roy crouched, and he turned on his witcher senses. Entwined, bright ribbons appeared in the air. These ribbons represented the trails of mice, lizards, vipers, roaches, and more critters, but none of them would lead them to any witcher or sorcerer, but Roy didn't give up. The grandmasters were experts in stealth. They could easily erase their traces.

The group made their way to the biggest area in the sewers. According to the map, it was in the center of the connected tunnels. For fifteen minutes they traveled, and junctions would appear from time to time, but the witchers did not split up. That would be a deathwish in uncharted territory.

The journey was quiet. Too quiet. There were no drowners or ghouls, who were regular residents of sewers. There weren't many mice around either. Plants that thrived in darkness were abundant, however.

Auckes was in the vanguard on the left. He stopped in his tracks and held his buzzing medallion, then he raised a hand, motioning for everyone to stop. He then crouched and held his hand over the ground. Quickly, he made an Aard Sign. The wind blew away the dust and soil, revealing a magical circle. It was as small as a plate.

A few Elder Speech runes were carved on it, and they were structured in the shape of a stream of flames. Just looking at it made them feel the heat.

Kalkstein took a look and said quietly, "Fire runes. Simplest magical trap in the book."

"So that means we got the right place." Roy held back the excitement in his voice, but the look in his eyes couldn't lie.

"Regular people, and a lot of witchers included, do not have the skill to set up this kind of trap. This must've been Idarran or Alzur." Serrit looked at his brethren solemnly. "We'll have to be a lot more careful from now on. If things go wrong, teleport away immediately."

There were untold dangers hiding in the darkness ahead. In just ten minutes, the group had found more than thirty traps. Fire, explosion, ice, and illusory magical traps aside, there were also regular traps like bear traps. Fortunately, with trap experts like Auckes and Serrit in the team and sorcerers like Coral and Kalkstein, the group managed to stay away from traps while making sure the traps stayed intact. Quietly but swiftly, they pushed ahead.

The deeper they went, the more excrements there were floating along the gooey river. There were also half-digested mice, snakes, and carcasses of bigger livestock like cows and goats. Sewers shouldn’t have this kind of stuff floating around. The question was, who brought these things in?

The group was advancing even more carefully, then the vanguard stopped in their tracks and held the buzzing medallions hanging around their necks. They held their breaths, and everyone stayed silent. Everyone looked ahead and saw something.

The shadow of a standing humanoid creature danced on the walls around the corner. They could see the outline of its back, legs, and arms. The silhouette was burly. Too burly. It was almost twelve feet tall, its head almost hitting the tunnel's ceiling. Its back was hunched, but it was big, and its waist was smaller. The silhouette had taut, mountainous muscles. It had no neck, and its pointy head was attached to its back. It was bent forward, giving the shadow a conical shape.

The group imagined an oversized mouse standing around the corner, and the changes in the shadow proved that. Every time it opened or closed its snout, the whiskers around its mouth would shiver like shaking iron needles. The shadow was holding something in its hand, munching on it.

There was a quiet crunching sound whispering in the air. If the group hadn’t been listening closely, they'd have missed it. The witchers had weird looks on their faces. From the shadow alone, they couldn't imagine what kind of monster this could be. It was obviously not a ghoul, drowner, or fleder.

This time, they couldn't skirt around this.

***

The group crouched a little and walked along the wall quietly. The Cloaks of Silence and double magical barriers covered up their scent and footsteps. They eventually saw the humanoid creature. It was a man-mouse. The burly man was wearing nothing, and his body was covered in a coat of thick, black fur. Its snake-like tail was twirled around his left leg, wrapping and loosening up. The creature's claws were like glinting daggers, and blood trickled from them. On the other end of its claws was a dead, rotting, blackening goat.

The creature held the carcass in its arms, its crimson eyes glinting with greed and cunning. It opened its mouth and ripped a shred of meat off with its sawlike teeth. As it munched on its food, the creature licked the blood off its fur with a barbed tongue.

***

Roy looked at the people behind him and grabbed a hand crossbow out of thin air, then he pulled the trigger without even aiming. A bolt hurtled through the rancid air of the sewers, drawing a straight silver line ahead.

The moment the bolt touched the man-mouse, its fur stood on end, turning it into a little hedgehog. It lashed out with its tail, and the tail left afterimages in its wake. Just like that, the creature slammed Roy's bolt away, but half of its tail fell to the ground. Before it could do anything more, a crimson light burst forth from the point of contact between the tail and the bolt, then it turned the towering creature into a red cocoon.

The silhouette of a swordsman danced on the walls. Roy's blade pierced the air and buried itself in the man-mouse, but the witcher stabbed the creature multiple times to be safe. The red of blood, the silver of metal, and the glinting runes shone in the air. When the witcher was done, pieces of flesh fell to the ground, steaming. The man-mouse was cut up into pieces.

Before it could even showcase its strength and speed, Roy had cut it down. The man-mouse's hideous head rolled over to Roy's feet, the ghost of its snarl etched on its face.

'Modified Man-mouse killed. EXP +300. Level 13 Witcher (17000/14500).'

***

Roy let out a rush of air and flicked the blood off his blade. He bent down and put a pair of leather gloves over his hands, then he rummaged through the insides of the mangled body. A moment later, he found himself holding an oval greater red mutagen. And a metal tag.

The tag was embedded in the man-mouse's back. On its surface, a line of indecipherable characters and numbers were engraved. It read, 'ULExIX0008.'

"Number eight…" Letho took another similar metal tag from his storage ring. "The insect we fought in Amell was number 22. Same letters."

"These modified creatures belong to the same series, then." Geralt nodded. "If I'm right, either Alzur or Idarran did this. Both are experts of mutation and genetic modification."

"This is a grandmasters’ product, but it's not just regular stitching of different parts together. The reaction that happened in its body is similar to witcher mutations. It was probably a cute little mouse before it was put through the experiment." Kalkstein held up the creature's head and observed its yellow, sawlike teeth. He grabbed a pair of tweezers and test tubes out of thin air and took some samples of its body fluid, whiskers, and body tissues.

Coen was staring at the darkness behind the man-mouse. The tunnel still showed no end. It was dark and rancid. There was something eerily mysterious about it, almost as if it were an abyss. He tensed up.

"I have a feeling this is the beginning, fellas. There'll be a lot of these disgusting experimental failures," said Eskel.

Coral pulled her hair back, her eyes filled with concern. "We've killed their pet. Alzur probably knows of our presence now. He must have set up traps for us."

"He might not be the one meeting us, though." Lambert smirked.

***

Like Eskel predicted, when the group was traveling down a multi-tunnel junction, a wave of mutated creatures jumped out from the darkness.

The silver glint of metal leapt across the air, clashing into a thick appendage. The tail was covered in green scales, and winds howled as it swung down on the steel sword. They clashed, and blood splattered across the air. The sword cut the tail open, but the impact from the clash pushed back the weapon.

A humanoid creature stood up. It was over six-foot-six and had an elongated head. The creature let out a thunderous roar as it pounced in the direction of the sword. The creature's tail swung around, stirring the gooey river into a pile of mess. The creature swiped its black claws, and it met metal. The blade and claws skidded off each other, sending blood and sweat flying everywhere.

The sparks from the clash illuminated the dark sewers, revealing the face of a bald man. There was an icy look on his face, then he quickly made a blue Sign with his hand. Letho pushed the Sign onto the ground, and a wave of magical energy surged from the Sign. Aard's power shoved the man-crocodile staggering backward, and a deluge spilled everywhere.

Letho stepped ahead, holding his blade up with both hands, then he swung it down on the creature's chest. The blade opened up a gash on the creature's stomach, and blood spilled everywhere, but it didn't seem to feel any pain. The creature wobbled for a while, then it opened its eyes wide. Like any cold-blooded predator, its eyes were amber. Once again, the creature swung its claws and almost metallic tail at the witcher.

A gust of gale howled across the corridor as the enemies clashed, spun, and clashed again. Sparks flew, sonic booms exploded. The creature's sturdy body blocked the sword's attack three times.

On the fourth swing, Letho grounded himself before he leapt high into the air, dodging the tail that was sweeping across the ground. He landed softly and thrust his sword ahead. The first strike hit the creature's nose, where its defense was the weakest. The second strike pierced its left eye and stabbed its pathetic brain.

Two towering silhouettes stood facing each other. A moment of silence later, the man-crocodile fell to the ground with a thud, stirring up a little storm of dust and shit. By reflex, the tail twitched for a while, then it fell still.

A bright light flared around the corner. Coen was making rapid gestures with his hands, and a crimson inverted triangle floated between his palms. Scorching flames charged ahead, turning the immediate area before him into a conical area of fire.

An irregularly shaped creature was wrigging before Coen. It was like a pile of mud with two sesame seeds shoved on its surface. The creature was burning in the flames. A foul scent of excrement came from it. The creature quickly shrunk and melted into a pool of black, corrosive goo.

***

On the other side of the passage, two Cats were surrounding a skinned creature with sharp bones protruding from its back. The creature resembled a graveir, but it had a pair of legs that were bent backwards like a fleder's, and it could jump high into the air. The creature let out screeches that could puncture anyone's eardrums as it leapt around the claustrophobic passage, but the Cats surrounded it in a web of deadly sword attacks, slowly drenching it in its own blood.

***

The Wolves were surrounding a mutated rock troll. The troll had fangs, claws, and something akin to a tortoise shell on its back. The Wolves danced around, casting Signs and attacking with their blades in perfect sync.

The troll's roars eventually turned into whimpers of despair.

***

The witchers kept Coral and Kalkstein safe, keeping them in the center of the formation. They were on support and dealing with anything the witchers missed. The light of magic shone and swirled around them. The sorcerers cast their spells, harassing and stunning the creatures the witchers were fighting.

***

Roy walked through a mountain of bloody corpses. Lying under his feet was a ground of corpses made up of chimeras and mutants. Some died from headshots, some were killed by having their vitals pierced after Roy's crimson tentacles wrapped them up. Some were cut in half by his energy slash. Some were crushed by his dragon's charge attack. None of these mutants could last a second against him.

The icy witcher held a hand crossbow in his left hand and dragged his sword with his right. He strode ahead, blood trickling down the edge of his blade. The crimson light surrounding him was merging into flames, burning the air quietly. He crossed the dark, squalid, and evil passage without stopping. Eventually, he came to a dead end. A wall covered in moss and vines. The witcher cast Clamp and dispelled the illusion before him.

Then a white bolt of electricity came hurtling through the air.

***

***