Sunrunner

My father is missing, and along with him, the Sunrunner family stone, Nausa.
My aunt swears this is common for him, but I know differently. Yes, my father is lost deep in his addictions, but he's never disappeared before. If it weren't up to me to handle the mess my family has made, I'd be a thousand miles away by now. But time is running out, and the threatening eruption of Mount Slate keeps inching closer.
Now, Half the Moonstriker family has come to help me look for Nausa, including Kit, a freaking assassin, and his brother Frost, the most beautiful man ever born. Frost almost makes me want to stick around, for the first time in my life.
But suddenly, nothing can go right. From a near-miss in the car to an ugly realization about my entire childhood, not to mention the way Kit Moonstriker keeps looking at me like he's deciding where to stab, saving the world isn't as simple as it sounds.
Sunrunner is the third in a series of four books, starring one beautiful mathematician ingenue, one bad boy who isn't so bad-he swears, and one overprotective brother who might be forced to teach him a lesson or two. It contains Caspian and Frost's HFN, and continues the overall story arc of the series.