The duology started out as a novella, then grew into a 75,000+ word novel, and was eventually split in two for aesthetic and convenience purposes.
Publisher's summary[]
Star Wars: Cloak and Dagger
Spanning years from the Empire's golden days to the fall of the First Order, this is a story of a broken child who fights wars her entire life - only to lose them all. Driven by revenge for the assassination of her parents, Ralia Arryn embarks on a journey through the ranks of the Empire's feared Imperial Security Bureau, keen on finding the murderer whose hand had held the blaster. Over a decade later, the mention of Colonel Arryn's name alone strikes fear into the hearts of rebels across the galaxy.
But everything has a price. Families break apart. Empires have a tendency to fall. As everything she loves is ripped away from her one by one, Arryn slowly descends from a sweet, careless child into a cold, ruthless monster who will stop at nothing, no matter how many lives are taken in the process.