"THE HOURGLASS DOOR," by Lisa Mangum, Shadow Mountain, 432 pages, $18.95

The fluidity of time has long been questioned. What would happen if time travel were possible? What would be the consequences?

In "Hourglass Door," local author Lisa Mangum's debut novel, those questions are put forth in a fantastical yarn than is sure to be a hit with fans of the young adult genre.

Abby is a typical high school senior. She has a loving family, the "perfect" boyfriend and friends she can really count on.

But life seems almost too perfect, and when Abby has the chance to apply to a small liberal arts college in the East, she jumps at it.

Abby's life takes an unexpected turn when a mysterious foreign exchange student named Dante moves to town. Soon Dante is part of the school play, and Abby is assigned to help get him up to speed.

The more time the two spend together, the harder it is to spend time apart. But there's something different about Dante, something Abby can't quite figure out.

Time begins to bend in strange ways, and Abby finds herself in the middle of a mystery reaching back to 16th-century Florence.

When she uncovers Dante's dangerous secret, Abby becomes the key to preserving both past and future.

It's inevitable that "Hourglass" will be compared to other books in its genre — a young heroine, mysterious and gorgeous stranger, and living on the cusp of danger.

Fortunately, that's where the similarities in story end.

In a time when copycats abound, Mangum has created a unique story with interesting characters and an intriguing plot. And because "Hourglass" centers on relationships, fantastical elements feel believable rather than, well, fantastical.

If Mangum's follow-up novels are anything like "Hourglass," which is the first in a trilogy, this new author will secure a solid place on the young adult scene.

E-mail: jharrison@desnews.com