Scorched (Scorched series, 1)

Sixteen-year-old Trinity Foxx is used to her grandfather's crazy stories, so she never believed the latest treasure he brought home was a real dragon's egg. Not until their home is invaded by soldiers trying to steal it and a strange boy who tells her the world as she knows it will be wiped out in a fiery dragon war--unless they work together to stop it. Meantime, there's a different voice whispering to Trinity, calling to her, telling her what to do...the dragon inside her egg is not ready to give up without a fight.