The Tower (Legend of the Heartstone, #1)

Those Who Enter Its Door Disappear
The Few Who Return Lose Their Minds

Reaching high above the cobbled streets, the Tower has loomed over the town of Savrsen for as long as anyone can remember. No one knows who built it or why, and no one seems to care—except Ena Novak. While most ignore the gray stone citadel, Ena has spent her whole life mesmerized by the Tower and the gentle glow of magic that only she can see emanating from it.

As her sixteenth birthday and the cusp of adulthood approaches...