Stone of the Sorceress (Book 2 in Saga of the Stones)

A year has passed since Siv and her friends became widely known as The Stone Keepers. Now, Massadonic has aquired another stone through his new wife Lolishall. The stone she has can control the weather and conjure great storms. Siv and her friends must travel to the neighboring country of Farshnig to try and find Massadonic and Lolishall, take the stone from them, and hopefully defeat them. Along the way they meet Samfing, the half-brother of Lolishall. Being raised as practically a slave by his half-sister, Sam jumps at the chance to escape her and Massadonic to find The Stone Keepers and help them defeat his sister. Being just a little older than Siv, the two become fast friends... and maybe more.