She obliged when the ICW called her in, accompanying the representatives as they "escorted" her to their headquarters to be questioned. Her wand was confiscated and she was left in a dark room with only a table and chairs for company for several hours. She forced herself not to pace, if she knew anything about Grindelwald, every minute they gave him would make him harder to find. Unfortunately she could only guess as to what he'd escaped to do.
Finally, a haggard wizard took the seat opposite her and they both sat in silence, Hermione had no doubt that there was a wizarding equivalent to one way glass and many more people were watching her invisibly.
'Where were you at seven o'clock yesterday evening.' He asked and she easily answered that she'd been showing the Malfoys around their new home with Harry. She related the story of how she'd collapsed and the state of her mind the next morning. The wizard noted this down, seemingly unsurprised. She wondered with some embarrassment if she really had been the only person to not realise Grindelwald could break the bond.
She consented to take Veritaserum, after which the questioning moved onto what they'd spoken about when she'd visited. She discovered then that she was one of those people that was very susceptible to the potion as she babbled on about her plans with the Malfoys and her History of Magic homework. The wizard tried to get a word in edgeways as she went on to describe the exact living details of everyone at Nurmengard. Eventually she did run out of subject matter and could finally stop talking, thankful that at least veritaserum inhibited blushing so the watching witches and wizards couldn't see how mortified she was.
The next question was carefully worded to only require a yes or no answer, as was the rest of the list because after the last debacle she only had a couple of minutes under the influence of the potion. She told them that he was not at Nurmengard and she hadn't received any communications with him. They almost had another slip up when the interviewer asked if they'd made any plans before his arrest but fortunately he was fast enough to tag on a hurried clarification before she finished drawing breath.
With the interrogation over, she was allowed to sit alone until the effects of the potion wore off. With her innocence established, it didn't take long for the ICW to put her to use as one of two people who knew Grindelwald better that the chapter in a history book.
They took her down to see the cell in case she could see some signature they'd missed. The dungeons were immaculate; the only sign that someone had even inhabited them until last night was the bed in the corner. They'd only discovered him missing when they'd come to deliver dinner and found the cell empty. The cell was still shut, the wards were intact, he'd even taken Hermione's arithmancy homework and text books. His wand was still stored securely in the artefact rooms and nobody was missing theirs. There had been no disturbances during the day, the guard at the door hadn't seen anyone unauthorised enter and the wards hadn't been breached.
The investigators were stumped, and as Hermione seemed to be their best chance she was given a grovelling, overly sincere apology for the interrogation and they almost begged her to look through his belongings to try and find a clue.
Knowing that she was at least partially responsible for his release – not this particular time, but if she hadn't been foolish enough to believe that such a simple bond could hold him... Out of a sense of guilt she promised to look through his belongings that evening and see if she could find any evidence of a bolt hole he might have run to.
They offered her aurors to protect her rooms that night but she refused them. The last thing she needed was anyone untrustworthy learning about some of the experiments Grindelwald had stuck to his walls. In her opinion at least, there were only two possible explanations. It was unlikely that Grindelwald had somehow managed to remove his bracelets and impossible that he'd escaped entirely without magic, so the only probable explanation was that he'd had inside help. That meant everyone in the ICW was suspect in her eyes.
Nurmengard was tense, everybody had heard the news and feared that their new found home might suddenly be taken away from them. Hermione gathered everyone in the auditorium to update them on the situation which did little to quell the fears. It was with a heavy heart that she tuned everyone's portkeys to take them to the British Ministry in an emergency before dismissing the crowd.
Back in their private rooms, she began the daunting task of sifting through the mountains of information in Grindelwald's room to see if he had any other safehouses. It was a long, slow task, especially because she knew that 1940's Gellert had been far to paranoid to leave such crucial information in plain sight. She had to check every innocuous parchment, book and box for concealment charms of every type. It wasn't enough to just check for the usual ones of course, Grindelwald had been no school boy and he certainly wouldn't have shied away from using blood magic to hide something important.
She gave up after the first desk full of items, throwing herself back on the bed and summoning tea from an elf. Usually she'd make it herself but she just couldn't spare the effort at that moment.
She realised that just searching the room would get her nowhere; he could build and ward an entirely new safehouse before she got half way through the pile. She needed to think like him, what place would Gellert and only Gellert be able to look?
Her eyes fell upon the racks of silvery vials and she realised that she'd probably just hit the jackpot. Unfortunately, she couldn't just go searching though that many visions of the future. There was a reason it was dangerous for non-seers to watch a vision and she'd struggled enough with just the one. The only person who could search through that cabinet was another seer and Grindelwald was, to her knowledge, the only one that powerful currently alive.
A traitorous little voice in the back of her head whispered that it would only be a fair price to pay. Her sanity for the security of the wizarding world, for the Greater Good and all.
She hurried out of the room before she could do something without fully considering it, leaving the tea cooling on the bedside. Her own room was a much safer thinking space.
She picked up the clothes that Ginny must have changed her out of when she collapsed the evening before and dumped them off her favourite chair. A heavy clunk and a fiery reflection drew her attention to the pile of clothing and she bent down to pick up the object curiously.
The vial of Grindelwald's vision glistened silver, not even a trace of black in its swirling depths. He hadn't betrayed them... so he wouldn't have broken their bond, unless he was protecting her from something.
Suddenly her search had a new direction and purpose. Gellert was out there somewhere and he was in serious trouble.