Stop me if you've heard this one: your average teenage boy turns out to not be so average. In fact, he has a few secrets he'd rather not be known by the common public, and they go a little beyond the normal secrets expected at that age. For one, he may not be entirely human...
Ever since the Dark Lord's demise at the hands of a baby boy, all wizarding folk become more wary of the so-called pure-bloods who made the bulk of You-Know-Who's army. This would usually not matter to Lyra Malfoy, a pure-blood herself, but as her final years at Hogwarts approach, she is becoming aware of the fact that maybe being a pure-blood is not all that it is cut out to be.