Two days into the summer break a large explosion shook Hogwarts to its foundation. No student had remained or they would have panicked. As it was, most of the faculty had yet to leave, and they were both scared and worried as small pieces of debris came falling on their heads. Most of the Professors were enjoying some quiet time in the staff room, after the explosion, they stood wands at the ready waiting for Dumbledore to appear, or hear the sound of the attack alarms, but nothing happened.

In the Headmaster's office, Albus Dumbledore and Minerva McGonagall were enjoying a cup of tea as they discussed school business when the explosion happened. For a moment, both stood wands on their hands until the Headmaster consulted with the castle. His connection let him know what happened, and immediately he dismissed the possibility of an attack. There had been an accident in the Potions Master’s workroom, and the magical entity that was Hogwarts required his presence in the dungeons to asses the damage. Dumbledore had chuckled a bit at the indignant tone of the castle, it was not often that Severus blew something; he had not produced anything that was heard beyond his workroom in at least five years. Still, when he did cause something to blow up, Longbottom’s continuous potions accidents became mere child’s play.

“Relax Minerva, it’s just one of Severus failed experiments. I’m heading down to see if he’s all right and asses the damage,” He commented walking towards the door.

“Merlin Albus! I think this is one of his worst,” She exclaimed still a bit shaken up.

“It probably was,” he agreed. He really could not remember one that had actually shook the entire castle. The dungeons were extremely well built and resistant, they had been designed to be the area where Potions Masters worked and experimented. “The castle is not happy with this explosion. I believe it’s because we haven’t had one this strong in years, it probably got used to the respite.”

“Doesn’t Longbottom blow things often enough for Hogwarts to be used to explosions?” She asked using her wand to clean dust that had settled in the office. Severus was always complaining about Neville’s incompetence in potions.

“So far Mr. Longbottom has not produced an explosion that the potions classroom hasn’t been able to contain. Certainly none that have shaken the entire castle, as this one seems to have.”

“You’re right of course. This time Severus outdid himself, there was even a little debris falling from the ceiling. I’ll have to remember to bring this one up whenever he complains about Mr. Longbottom’s way with potions.” She smiled a bit, knowing the Potions Master was not going to be happy to be reminded of his failed experiments. It grated him to fail at anything.

“I’ll have to be present for that one Minerva,” Albus chuckled, he could already imagine Severus sputtering at trying to find a come back for something like that. Knowing him he would probably just storm out of the room robes flying.

“I’ll be sure to let you know in advance if possible,” she was thoughtful for a moment. “It’s strange that we haven’t heard from him yet,” she mused and began to feel the slight tingle of worry. “He’s usually reported almost as soon as the explosions happened, and he hasn’t yet. I’m having a bad feeling about this, I hope he wasn’t hurt.”

“You know he’s always careful with volatile concoctions. I’m sure he’s alright, Severus is probably ranting as we speak, and no doubt he’s already analyzing what went wrong. Would you be a dear Minerva and please reassure the rest of the faculty and the house-elves that there’s nothing to worry about?”

“Of course Albus, just go check on him already. He might be injured.”

With that, Albus Dumbledore went out of his office; Fawkes saw fit to accompany him on his way to the dungeons. The Headmaster did not like what he was seeing as he walked to Severus workroom, there was a lot of small debris and dust all over, a frown settled on his usually jovial face. The closer he came to the dungeons the worse things began looking. The golden phoenix on his shoulder began thrilling with worry, and the old wizard could not help but feel worried too. What he found when he finally arrived to the dungeons staircase was worse than he expected, it began looking like a battleground.

Parts of the staircase were gone; part of the ceiling had caved in. As he approached the Slytherin dormitories, there were more signs of destructions. Areas of the hallway leading to the potions classrooms, the storage rooms, Severus quarters and the deepest parts of the castle where the Potions workroom were located were almost completely blocked by large pieces of the ceiling and walls, the dust had not even settled yet and it was hard to see clearly and breathe.

The old wizard could only stare in shock as he tried to make his way through all the debris. The destruction was evident, and the fear that this time his Potions Master had not survived settled. None of the younger man’s experiments had caused something remotely like that, in fact he had not heard of a previous collapse of the magnitude he was seeing. He came to an area that had completely caved in and blocked his way to the Potions workroom.

The Headmaster talked to the castle again; he asked it to locate Severus, and asses his condition. He really did not want to believe the younger wizard was dead, but… No he would not give up the hope that his Potions Master was still alive. To his surprise, Hogwarts was not able to sense anything of the area; the castle was more than slightly worried at this. There was some kind of disruptive magic that had blocked its access to that part of itself.

Hogwarts was becoming increasingly worried as it checked the condition of its wards and protections; and what it found was not good. Several of the most important wards were either gone or severely weakened. The foundation of the wards had been tied to the first foundation stone of the castle, deep inside the dungeons. Quite a large number of the other wards that had been added later had either been built using the foundation stone or the original ones as a base. There were of course many other wards to protect the school added by some far sighted individuals, but still the strongest had been tied to the area. In lieu of the events the castle did the only thing he could, it raised and strengthened those wards that it could control. Some key areas of it were sealed for protection.

Albus was extremely worried now, he could not move forward, and Hogwarts was putting itself on high alert to make up for his weakened protections. To keep on going he would need the help of all the house-elves and the Professors still at the school. He hoped they were enough to rebuild the area and find Severus. It was also imperative that what had just happened remained a secret; a weakened Hogwarts was an easy prey for Voldemort and his Death Eaters. Even without students capturing the school would be a demoralizing blow for the wizarding population.

“Severus!” Albus called through the rocks. He hoped the young wizard was merely blocked from accessing the outside part of the collapse. “Severus, are you all right?”

When several attempts at getting a response failed, Albus decided to call the other professors and the house-elves. They would have to dig their way to the potions workroom and hope they would find Severus alive. His Potions Master had managed to survive quite a lot of things so he clung to the hope the younger man was probably either stunned or unconscious. After using the sonorous spell, he spoke.

“All professors still at Hogwarts are required at the dungeons entrance; there has been a cave in, and some damage. Head house-elf, report to me immediately. The rest of the house-elves are also required at the entrance of the dungeons.”

Albus Dumbledore then assessed the task as hand, with what little help Hogwarts could provide at the moment. They could not risk banishing everything outside; the higher levels of the castle might be affected. The dungeons were, after all, the whole foundation of the building. Accidentally removing a supporting wall or beam might result in worse structural damages that could compromise the stability of the whole castle. Taking this into consideration, he began carefully and meticulously removing the huge pieces of the castle that blocked his path, as he cast a few spells to strengthen the parts of the ceiling and walls that remained.