Bless J.K. Rowling. Whatever you think of the Harry Potter series, those books inspired a whole generation of young people to turn away from televisions and game machines and read.

In addition to that, the Potter series created a new market for young-adult books that have inspired the best authors from fantasy, mystery and other genres to write for the 9-12 range. Now, Holly Lisle has entered this auspicious group with a trilogy beginning with The Ruby Key.

Her premise is that humankind only ventures forth by day. Should any go about by night, they are subject to the nightlings, elven creatures with magic who would enslave or kill them:

Mankind is Sunkind
And rules by the light;
Sunrise to sunset,
No less, and no more.
Nightlings are moonkind
And rule in the night;
Sun's set to sunrise,
Or there will be war.

But, young Genna, 14, and Dan, 12, of the village Highrush, are out after dark the only night they can be. This is the night that the humans give their offerings to the nightlings. They give their best and, in return, the nightlings give them trinkets and baubles.

The sibs have risked being taken as slaves by the nightlings to save their mother. They've made their offerings quickly and are sneaking out to secure some sap from the magical taandu tree, which they hope will cure their Mama, who has fallen ill. They have already lost their father, the former caer of the village, and fear he is dead.

As they are attempting to gather the life-giving sap, they encounter a nightling girl who tells them a tale of treachery. It seems, their "Uncle Banris" who's taken over the job as Highrush's caer since their father disappeared has made a deal with the nightling leader, Kai Letrin.

Banris wants to be immortal and doesn't care who he kills to get there. The sickness, or saku, that is effecting their village and their mother is a result of this deal. Banris isn't quite immortal yet -- he must wed their mother and kill their whole family to achieve his gift.

It's up to young Genna and Dan to make a new deal with the Kai to save their family and village. They are told by their nightling ally that Letrin will ask for something impossible, but not to worry -- the rebel nightlings will give them aid. All the nightlings ask of Dan and Genna in exchange for this help is to ask for the Ruby Key.

Genna manages to secure the deal she sought. All she has to do is find one person, the child Doyati, and return him to the Kai by the dark of the moon.

Simple, right? What the Kai didn't tell them was that they'd have to learn to travel on the moonroads, magical roads that can take you anywhere, if you know how to manage them, face a warrior bard, the blind hunt, a dire worm and other adversaries.

But they will have help. The young nightling girl will aid them as much as she can -- and a talking cat will come to guide them.

As always, Lisle crafts a story with gem-like beauty and precision of phrase that will keep anyone from 9 to 90 reading late into the the night. Her writing is beautiful, almost poetry in itself:

I know the quiet beauty of apple blossoms in Spring. I love the sweet awkwardness of newborn kids and lambs, the comfort of a cushioned rocking chair, the serenity of a shake roof on a rainy night, and of sturdy stone walls and a fire on the hearth come winter. These are good things, but simple.

Like many of the young-adult novels today, Lisle's story also encourages and demonstrates the values of honesty, mercy, teamwork and friendship. Even the cat is a very likable member of the crew.

Yes, this is the first book of a trilogy, but Ruby Key stands alone enough that you will get a satisfactory conclusion. Lisle has cleverly built in a future for both Genna and Dan that will want us to read both of the future books -- and hope, like many other fantasy writers, Lisle will extend the trilogy to a longer series.