The Forbidden Magic at Hogwarts

It is Harry Potter's seventh year at Hogwarts - Voldemort was killed in battle by Harry and the Order of the Phoenix last year and, except for Albus Dumbledore and Severus Snape, everyone survived the final fight.

Now, with the castle varying between mourning for the dead and jubilation, a lone figure is easily able to sneak away from the Common Room, down to the library in the middle of the star-filled night, and smoothly into the Restricted Section without setting off any alarms...