Books in the Wings of Fury series

"Althea Lambros is growing into her power, wrestling with a burdensome heritage, and unwilling to concede to Cronus, the redoubtable God of Gods. For that, Cronus is making good on his promise. Calling upon the elder Titans, he's bringing down his wrath on the world ... With the help of her friend Theo, Althea takes cover with her sisters, Bronte and Cleora. But they can't hide forever. To mastermind the downfall of the evil king, Althea must recruit allies of her own before the aggrieved mortals surrender the sisters to Cronus in exchange for peace"--