Gaara is one of my favorite Naruto characters. In the manga / anime, his development from villain to hero is amazing. He learns that he can be loved and that he can love - and that is what this story focuses on.
This story is set after the manga / anime and is set during Gaara's time as Kazekage - mostly when it is just beginning. Gaara is learning that although he is the Kazekage, the true power lies with his council of elders and the Daimyo. He has to do what they want in order to keep Sunagkure prosperous.
This leads to the elders telling Gaara he has to marry someone, and then choosing someone for him to marry. Gaara goes along with it because he doesn't have much of a choice.
Gaara meets his future bride, but then she is kidnapped. He goes along with his future sister-in-law to find her and bring her home. When they find her, Gaara has already figured out that the man who kidnapped her was the man that she was in love with, and they were actually trying to run away together, rather than a kidnapping.
Gaara, although he is disappointed that he will never get a chance to learn to love his future bride, understands that he has to let her go, rather than haul her back tot he village and force her to marry him.
It made me feel so sad for Gaara. He wasn't in love with her, and he still doesn't really seem to understand romantic love, but he wanted to try. He was ready to try, and it just gets taken away from him.
There is also a sub plot where younger ninja trained by Kankuro are loyal only to Kankuro and want him to overthrow Gaara and become Kazekage. Kankuro plays along, with Gaara also knowing (though this isn't revealed until later), so that he can flush out who is actually behind it.
The story also show a bit more of how Sunagakure and the Daimyo interact, even though we don't see the Daimyo in this story. It shows how the economy works, especially during a time of peace between the 5 great nations.
* the copy I have is an unofficial translation, so maybe some things get lost / the language doesn't flow as well perhaps as an official translation.