Shadowblood Heir

Finish the series or it will finish you.

When bestselling author Patrician Martinez dies the same day as a major character in the televised version, superfan Matt Lee thinks she prophecized her own demise. Haunted by visions and questioning his own sanity, Matt needs to convince his friends to help him solve the mystery. Because if he's right, Shadowblood isn't mere fiction; it's a warning, and his favorite author left a message for someone to take up the fight after her death.

If he's wrong, it means that Matt is losing his mind.

Of course, if shadow magic is real, and Earth is about to be overrun by invaders from another universe, it's possible that Matt could be both right and insane.