Star Wars: Thrawn Ascendancy: Book I: Chaos Rising

The peace of the Ascendancy, a beacon of calm and stability, is shattered after a daring attack on the Chiss capital that leaves no trace of the enemy. Baffled, the Ascendancy dispatches one of its brightest young military officers to root out the unseen assailants. A recruit born of no title, but adopted into the powerful family of the Mitth and given the name Thrawn