Who is William Wilde? And what’s the story about?

Here’s the early blurb for William Wilde and the Necrosed, book 1 of The Chronicles of William Wilde:

Eight months ago on a cold winter’s eve, William Wilde became an orphan. A simple car accident that killed his parents and his brother. Or so he thought.

On the first day of his senior year, Serena Paradiso enters the halls St. Francis High School and William’s life. A beautiful girl with secrets related to the death of his family. The same secrets kept from William by his best friend: magic flows in William’s blood, as well as a poison that may ruin him.

And on the first day of Christmas break, Kohl Obsidian, a Necrosed—an undead terror created for killing beings imbued with magic—re-enters William’s life. Monstrous, misshapen, and the author of much death and destruction, Kohl won’t rest until the tragedy he started on that cold winter’s eve eight months ago finally ends with William’s death and the theft of his magic.