'Notebook' pivotal for McAdams.

Byline: BILL THOMPSON

Consult the closest encyclopedia. Go ahead, we'll wait. That's it ... Volume L. If a photo of Rachel McAdams does not adorn the entry for "lovely young actress," return the book for a refund. It's an absurd omission.

All the hallmarks are there. The fresh face and 10-candlepower smile. Silky voice. Tinkling laugh. Great figure. A breezy enthusiasm that could charm a cobra, not to mention a cast, crew and onlookers at a downtown set.

It's a sparkling clear day on Broad Street, and even at rest, McAdams looks for all the world like a star in the making, something the stage-trained, Ontario-born actress fervently would like to realize with "The Notebook," her first leading role in a major mainstream picture.

Set in the coastal Carolinas, the film is drawn from Nicholas Sparks' best-selling novel of the same name, bearing his signature romanticism but with characters expanded and deepened in the screenplay.

"It's just the most beautiful love story," says McAdams, distinctively turned out in …