By chipped purple nail polish
"Students, you will have thirty minutes to complete your mid-term exam. This grade will impact your GPA greatly, so please take this exam seriously. Yes, Ms. Patil?" the Arithmancy teacher, Professor Vector, a short, stocky grey-haired man whose glasses gave you the feeling he closely resembled a barn owl, asked. "No, Ms. Patil, we are not offering a makeup test- this is your one and only chance to take it. Time begins- NOW!"
Hermione Granger sighed, looking at the exam in front of her. She tried to concentrate on the questions, but her brain was slipping, until she found herself thinking, quite worriedly, of Harry Potter and Ronald Weasley, her two best friends in the entire world, who were off doing who knows what all over Europe, searching for the three remaining Horcruxes. Hermione had remained behind, returning to Hogwarts to keep an eye on things there and to study to become a healer, although she wasn't quite sure if she even wanted to do that anymore. So much had happened since her career-advice appointment with McGonagall in fifth year that her attitude and perspective on life had changed quite a bit.
The last she had heard of her friends, they were in Ireland, following a trail that, they believed, would reveal the Hufflepuff's cup once owned by Hephzibah Smith. But that was three weeks ago, and although Hermione knew they were okay, part of her still worried for them night and day...
Suddenly, the timer went off that Professor Vector had set for the exam. Jerking out of her thoughts, Hermione stared around. She had only finished about three fifths of her exam. Appalled at herself for being so lax, Hermione sat back down at her desk, and, head bowed, began organizing her parchment to get her mind off her slowly sinking grade point average. But already she could see her beautiful, perfect A sliding slowly down to a horrible, awful B.
"I will grade these exams quickly, and then pass them back," Professor Vector announced. Hermione felt her lips trembling slightly. Opening up her bag, she pulled out several quills and began to clean them with her wand. By the time she had finished, Professor Vector had completing grading the tests.
"The scores were lower than expected, but that is no big deal... We will review what we have learned so far next week to give them a firmer hold on your minds. This is, after all, a N.E.W.T. class."
Hermione caught her exam as it fluttered past. And she stared at it. And stared at it. And stared at it. She was horrified. She had never gotten a worse grade in her life!
Because on the top of the page, in bright red ink and perfect cursive, was a devastating C.
The bell rang, and Hermione, packing at top speed, ran from the room, toppling into Justin Finch-Fletchey on her way out. She hurried to the seventh corridor, tears rolling down her face as she sprinted down the marble hall. She had never been more humiliated in her life. All of her past stress, worrying about her friends dying and the world being taken over by Lord Voldemort poured out as she paced across the blank stretch of wall back and forth three times, thinking forcefully, I need a place to hide my test so no one will ever see it... I need a place to hide my test so no one will ever see it...I need a place to hide my test so no one will ever see it...
Still sobbing, upset over everything that had happened, Dumbledore's death, Sirius' death, Tonks' murder the month before... All of the heaviness that had weighed on her heart since Cedric Diggory had died came pouring out as she wrenched open the large oak door that had appeared and ducked inside, choking.
The test was balled in her left fist as Hermione looked around her. She had walked inside what looked like a giant atrium, large enough to fit at least four muggle football fields inside it. Hermione's tears slowly stopped as she stared around. Centuries of hidden, forbidden objects were everywhere, piled in hills of things. Hermione dropped her test on the floor as she surveyed the room. Pausing, she turned to an ancient wardrobe on her left. Curiously, she opened it, and peered inside.
There was a large, moth-eaten bathrobe and an old invisibility cloak. Opening her bag, Hermione slipped the invisibility cloak inside it. She shut the door and continued on, stepping over piles of books and eerie Dark objects, when a glimmer of gold caught her eye. Taking two lateral steps, Hermione found herself in front of a large bookshelf, covered in spider webs and what looked like dry maple syrup. A dusty old cauldron rested on the bottom shelf, full of what looked like the ingredients for Polyjuice Potion. The second shelf held a pair of black gloves and an ugly, bumpy necklace made of what looked like acorns. But it was the third shelf that intrigued Hermione. It was what laid on the third shelf that made her eyes widen with a mixture of anxiety and glee.
Hermione reached her hand up through a large, sticky, silky spider web and, wrapping her fingers around its golden, dusty base, pulled the Time-Turner off of the shelf. Its silver chain had snapped from age, but Hermione easily repaired it with a simple spell. It was of different make than the one she had used in third year; she supposed this one was older. Nonetheless, it would still do as she wished it to. Stowing it carefully inside her stolen invisibility cloak in her bag, Hermione ran out of the atrium, staring back over her shoulder at three century's worth of hidden treasure before opening and shutting the door behind her.
Once back in Gryffindor Tower, Hermione hurried to the dorm. Her roommates were in History of Magic, and although Hermione generally detested ditching, she realized that this was a rare occurrence. And, anyway, it wasn't everyday you found a hidden time-turner that could change the world.
Because Hermione already knew what she would do with the Time-Turner. She had known it since she had seen the glimmer of gold in the atrium; she would go back in time, to 1944, and kill Tom Marvolo Riddle before his reign of terror could truly begin...