Abi is the middle child of two Heralds. One is Amily, the King's Own Herald while the other is Mags, publicly another Herald, but in actuality, the King's Spy Master. Given her unique upbringing, even though Abi hasn't been chosen as a Herald herself, she has still been taught a specific set of skills that not only help her father's spy network but also allow her to be Princess Kat's bodyguard, something she has trained for since she could hold a knife.
Abi was fine not being a Herald and not having any Gifts, but she was getting a little jealous of her older brother's recent adventures outlined in The Hills Have Spies. Except, one day her Gift manifests itself, and it is one that no one has heard of before. When a wave of sickness falls over Abi while she and Kat are crossing a bridge, she knows the structure will soon fall. The pair clear the bridge before it collapses and they are praised as heroes. Granted, Kat gets most of the credit, but Abi doesn't mind, she's a spy after all and prefers to be nondescript.
When the local school of Artificers gets word of Abi's ability to sense the imminent weakness of structures, they ask her to join their classes. If she can better understand how structures are built, then she should be able to communicate issues to those that know how to fix it. When she develops her own passion for building though, she finds that she could become a Master Artificer in her own right and as she learns to hone her ability, she could become a major benefit to Valdemar as a whole, not just her father's spy network.
A major portion of Eye Spy is Abi's schooling in building and training her Gift, but what kind of Valdemar tale would this be without a little adventure thrown in for good measure. Before the book is done, Abi is sent with a delegate of Artificers to the Valdemar border in order to help improve relations with neighboring towns. While the adventure Abi has might not be quite as epic as Perry's own in Family Spies - Book One, it still ends up being fraught with danger, plus a few interesting building-related puzzles that need solving.
Eye Spy: Valdemar: Family Spies - Book Two is a fun adventure and works well as not only a continuation of the previous books in the series, but also as a mostly stand-alone novel. While you should know the Valdemar backdrop to understand the relationships of Heralds to the country and what they do, it isn't explicitly necessary to follow Abi's journey, and while the adventures in the previous novels do come up, again, any details that might be relevant are touched on. But for the most part, this is Abi's story much like the previous one was Perry's. If this trend continues, I'm interested to see what the next volume has in store for Mag's third child, Tory, and his unusual flavor of FarSight.