Harry Potter didn't expect that what he said to the Black brothers and sisters in order to raise their vigilance would ignite the fighting spirit of the two brothers.

As a child who grew up in the mountains, since he was a child, he followed his friends in the village to catch bamboo rats in the mountains, fish in the river, help with farm work, and occasionally follow the candidates who are preparing to take the college entrance examination into the mountains to hunt wild boars.

However, Alsace's first brain-hole plan was immediately rejected by Professor Rodney. Although no one smokes in Hogwarts, fireplaces and candles are still everywhere. If you really want to pour carbon monoxide into the pipes like Arthas thinks, you will blow up Hogwarts first.

When Rodney returned home that night, he sent an email to Zhang about this incident, which frightened Zhang Mou, he didn't expect these two children to bear so badly.

However, Zhang soon understood what the problem was, and he was worried that the brother and sister would go through the secret passages that he had filled with carbon monoxide in order to prevent the Death Eaters from invading, so he told the two of them about the physical traps in the secret passages, and the two of them are now doing the same.

The two siblings would not be knocked down by this small setback, and soon Gianna came up with a new solution.

The next day, Sunday morning, Neville made a routine visit to the greenhouse area to take care of the herbs inside.

The corners of Neville's mouth curled slightly as he walked to the greenhouse, and then carefully observed the broken defenses around the greenhouse.

Neville examines a slumped vine that normally turns into a tentacle play if an animal touches it. He looked up a short distance ahead, where a small potato emerging from the dirt had a shallow shoe print, apparently a levitation charm cast on him by the person who walked by. And the cacti, which shoot spikes as soon as people approach the greenhouse, are covered with dewdrops, just like the fat house happy water that has just been taken out of the refrigerator, and it is obvious that they have just been frozen.

"It's a veteran!" Neville thought that in the last two or three years, he hadn't met a student who could break through the first line of defense so cleanly.

So he cast an illusion spell on himself and walked towards the greenhouse.

The intruders apparently did not hide their presence, not only did they hang a sign saying "There are people inside" at the door of the greenhouse in accordance with the relevant regulations, but they also wrote their names in the visitor registration book hanging next to the door, and the visit was written "Extracurricular Investigation".

Walking into the greenhouse, Neville saw that Arthas and Gianna, each in white coats, were holding a small notebook, discussing something while writing and drawing in the notebook, and from time to time he took out the book to look through it.

Neville listened behind them for a moment and noticed that they were recording the poisonous herbs in the greenhouse, such as which herbs were poisonous when burned, which herbs were fine in contact with the skin but poisonous when eaten, which herbs were the opposite, and so on.

The siblings were then taken back to the office by Neville.

In his office, Neville looked at the two siblings with a blank face, and on the desk sat a notebook of the two of them, on which they recorded more than half of the poisonous plants in the greenhouse.

"Tell me, what do you two want to do?"

Because a few years ago, there was a conflict between classmates at Hogwarts, and as a result, someone stole poisonous herbs from the greenhouse to poison the enemy, so Neville had to pay attention to this matter.

If the two of them mixed several poisonous herbs to make a volatile compound poison, there would be a group incident.

"Winter is coming, so let's make a note of the location of the poisonous herbs so that we don't get it wrong when it's dark." Alsace's excuse is very much in line with Zhang's usual style.

Neville glared at Arthas and said, "Didn't anyone tell you that non-toxic and harmless herbs are grown in special greenhouses, and poisonous and harmful herbs are grown in special greenhouses?" ”

Alsace was about to say "no", but he realized that Professor Longbottom had said it in the first herbology class.

Neville continued, "If you don't want to be tied to a chair and watch all the equipment and potions in your warehouse be dismantled or sold at auction at a low price, I advise you to be honest. ”

This trick was told to Neville by Zhang, and Neville didn't know if it was good or not, so he tried it first.

So Arthas relented.

Arthas said: "Yesterday Mr. Potter came to us and he told us about the snake. ”

Neville was stunned for a moment, and then secretly relieved, he didn't want to do it to the other classmates, but he didn't plan to let the two of them go.

"So you're going to find some poisonous herbs to protect yourself?" Neville asked.

The siblings nodded.

"Slytherin deducts twenty points." Neville immediately deducted 10 points from each of them, "Regardless of your motives, you have violated the school rules that prohibit entering the poisonous herb greenhouse, and you will be punished." If you need herbs from the greenhouse, you can send the application report to me or the principal. Of course, I can't guarantee that it will be approved. ”

Eventually, the siblings left Neville's office with a large stack of herbal exam papers.

The two sat on the grass by the lake with their heads down, kept touching the small stones on the ground, and threw them into the lake.

"Alas...... The poisoning plan failed. Gianna, who was sitting on the ground, held her bent legs with her left hand, pressed her chin against her knees, and felt the small stones on the grass beside her with her right hand.

Her plan is to make two kinds of rat poison that rats love, and use the opportunity for snakes to eat large quantities before hibernation to get Nagini to eat the rats with medicinal powers. Rats that eat these two poisons separately are fine, but when the two powers converge in Nagini's body, they become violently toxic.

However, this plan is not working now, as Neville strictly forbids the two of them to approach the greenhouse area during extracurricular hours.

"Poof!"

Arthas threw a slightly larger stone from the Flying Charm into the lake, where a silver-white woman's head emerged.

The goddess of the water did not ask Arthas if you fell into the water with the sorrow of frost or the joy of fire, and the weeping myrtle looked at him with tears in her eyes, "Why did you stone me!" ”

The resentful look in the myrtle's eyes condemned Arthas's conscience greatly.

"I'm sorry, Myrtle." Arthas hurriedly apologized, "I didn't know you were under the water. ”

Then Myrtle began to howl and cry, "yes, who would have thought that a funny Myrtle would be in the water? Who would have thought that she would be flushed down the toilet by Peeves, down the drain and into the bottom of the lake, and then stoned? ”

Arthas stood on the shore helplessly and watched the myrtle crying in the water, not knowing for a moment how to comfort her.

After crying for a while, Myrtle re-entered the water.

Gianna stood up and walked over to Arthas's side.

"Did you hear anything from Myrtle's words just now?" Gianna asked.

Arthas nodded and said, "Tell me what you think." ”

"The sewers of the castle are connected to this lake, and we can make a fuss about it." Gianna said.

Then Arthas looked at his sister in horror and asked, "Are you trying to plug the drain outlet of the sewer and drown Nagini with the water that flushes the toilet?" ”

"Don't think I'm so disgusting!" Gianna glared at her brother in disgust.

Gianna crouched on the ground and drew a diagram on the ground with her wand.

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"It's a complex plumbing system under the castle." Gianna pointed to the circle below the castle, then she pointed from left to right, "This is the sewer that leads to the bottom of the lake, and this is the water. ”

"We suspect that Nagini spends most of his time living in a vault under the castle, and the passage to the chamber is connected to the pipe system."

"If we find a way to connect the sewer and other pipes under the water level of the lake, for example."

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Gianna changed the schematic diagram on the ground for a moment, and then continued, "So that the lake can pour into the chamber under the castle inside, and we can drown Nagini while she hibernates." ”

"But we don't know where the pipes are going under the castle, and we can't get into the sewers." Alsace said.

"We can get Peeves for help." Gianna said.

At this time, the brother and sister did not realize that a cat had already walked up behind them lightly, and had been listening to them discuss the plan to fill the secret room with water for a long time.

Two hours later, the brother and sister left the principal's office with a stack of Transfiguration homework in their hands.