Mutant Serum

When they rushed to the fourth floor, they found that there was no one on the fourth floor.

Only a shattered zombie remained from the explosion.

At the same time, after the explosion on the fourth floor, a sharp angry roar suddenly echoed from the fifth floor.

The remaining zombies on the fourth floor saw humans and immediately pounced.

These were just first-level zombies and posed no threat to the twin brothers.

Bang, bang, bang!

Several gunshots rang out, and the zombies fell one by one.

After dealing with these zombies, a heavy object fell near the fourth-floor staircase.

As they looked, everyone's pupils shrank.

They saw a female spider zombie with eight sharp, long legs, rushing down.

Hiss!

As soon as the spider zombie saw humans, it opened its mouth wide, emitting a threatening hiss.

Clack, clack, clack!

The three men with guns subconsciously started shooting.

But what terrified them was that the bullets hitting the spider zombie didn't cause any damage at all.

Its skin was as hard as rock, and the bullets left only faint marks.

Although they didn't harm her, the spider zombie was clearly in pain and hissing wildly.

Plop!

At that moment, the spider zombie's abdomen split open like a mouth and spat out a bluish web.

The web rushed toward them, and the twin brothers immediately dodged it.

But the three men with guns by their side couldn't escape.

The three of them were bound by the web and struggled in vain to break free.

At the same time, the spider zombie crawled along the wall, hanging upside down from the ceiling, heading towards the twin brothers.

"Attack!"

The twins looked at each other and shouted.

Sizzle!

In the next moment, their combat knives emitted a flash of lightning.

The knives were filled with lightning, making them incredibly powerful.

With one on the left and one on the right, they charged toward the spider zombie.

The unusual sound of the battle on the fourth floor attracted Bai Mang, who was hiding in the bathroom.

They slowly walked out, then looked up the stairs.

"Humph! Let's wait a little longer; we'll go upstairs to reap them later!"

Bai Mang grinned.

Bang!

Just then, Zhang Dian fell directly from the staircase, his body covered in wounds.

Zhang Dian, who had fallen, saw Bai Mang and the others waiting for him and shouted, "Brother! Run! They're coming downstairs!"

Bai Mang didn't hesitate and immediately raised his weapon to strike down Zhang Dian.

In an instant, Zhang Dian's head rolled away from his body.

At this moment, Zhang Lei saw what happened downstairs, and was preparing to come down for revenge.

"Bai Mang, I won't let you off the hook!"

Just as Zhang Lei was about to rush downstairs, the spider zombie upstairs kicked him with a powerful blow.

Bang!

Zhang Lei was sent flying and fell out of the fourth-floor window.

At the same time, the spider zombie noticed Bai Mang and the others below and immediately changed its target to attack them.

"Attack!"

Bai Mang didn't hesitate and led his group in charging forward.

At this moment, across the street from the research institute, Xiao Feng clearly saw everything through the scope of his Barrett.

As the battle heated up, Bai Mang and his sister, one on the offensive and the other as support, combined with the assistance of other firearms, managed to kill the level three spider zombie.

After the spider zombie fell and didn't get up, Bai Mang pulled out a small knife and dug out a blue crystal core from its head.

A third-level blue crystal core.

This core was filled with an energy of twenty thousand.

The first-level cores contained a thousand energy, white color.

Second-level green cores contained ten thousand.

And third-level blue cores contained twenty thousand, and the higher the level, the purer the energy.

Generally, you couldn't exchange a green core for a blue core, even though they appeared to have the same value. Green cores had a higher energy purity, which was crucial for certain equipment.

Some shelters had even invented battle mechs, and the minimum requirement for the mechs was the purity of a green core. Otherwise, the energy of the white cores would be depleted in seconds.

Seeing that blue crystal core, Xiao Feng couldn't help but lick his lips.

"Quickly, check if Zhang Lei is dead!"

After dealing with the spider zombie, Bai Mang immediately instructed the others.

However, when someone came to the window to look down, they found no one below.

"Boss, bad news, Zhang Lei is missing!"

As they looked, they saw a limping figure in the distance slipping into the sewer and disappearing.

Bai Mang frowned, then said, "Don't worry about him, let's go upstairs and see if there's any of that mutation serum!"

However, when they arrived on the fifth floor, they found that a safe had been forcibly broken open, and it was empty.

"Where's the serum? Dr. Jia said it was in the safe on the fifth floor!"

"Could it be that this place was already searched?"

Bai Zhi asked in suspicion.

"It's possible! When we first arrived on the first floor, we saw the corpses of zombies; this place may have been searched."

Bai Mang sighed and said disappointedly.

"Let's go! Our efforts of the past half month have been in vain. If we had that mutation serum, we could have cultivated another Evolver in our shelter!"

Then, they left the research institute in disappointment.

Once they had all entered the sewer, Xiao Feng sneaked into the research institute.

He had already seen everything clearly from his perspective when Zhang Lei and Zhang Dian fought on the fourth floor.

At that time, Zhang Lei had restrained the spider zombie while Zhang Dian immediately rushed to the fifth floor, then took something out of a safe. But just now, Bai Mang and the others went up to the fifth floor and left in disappointment.

Clearly, they hadn't found what they were looking for.

On the fourth-floor staircase, Xiao Feng arrived in front of Zhang Dian's body.

He searched for a moment and found something.

When he took it out of his pocket and looked at it, he saw that it was a glass vial containing blue liquid.

"What is this?"

Xiao Feng immediately used his system to check the information on this serum.

Mutation Serum: After use, there is an 80% chance of awakening the user's abilities and a 20% chance of death. If used by a zombie, it will undergo another mutation.

"Good stuff, this is good stuff!"

Xiao Feng immediately smiled.

However, he had already evolved into an Evolver, so it might be a waste to use it on himself.

Without thinking too much, Xiao Feng immediately used Instant Return to return to his resturant room.

Just as Xiao Feng had returned, there was a knock on the door from outside.