Veronica (Kristen Bell) will mix high school socializing with solving mysteries.

"Veronica Mars." Tonight at 9, CW.

Like "Buffy the Vampire Slayer" before it, "Veronica Mars" is moving from one network to another, while its heroine makes the equally tricky transition from high school to college.

On its new network, CW, and in her new environment, "Veronica" blossoms.

After surviving the demise of UPN, "Veronica Mars," created by Rob Thomas, begins its third season tonight at 9 - with a significant readjustment. Veronica (Kristen Bell) is starting her first day at Neptune’s local Hearst College, and is thrown into the world of giant lecture halls, well-manicured campus quads and cliquish sorority halls.

But she’s a commuter student, so she lives with her dad (Enrico Colantoni), who still runs his own private eye agency. It’s no surprise, then, that Veronica is solving mysteries in class, and pursuing them out of class, in no time.

The new season reunites us with some familiar faces, most notably boyfriend Logan (Jason Dohring), longtime buddy Wallace (Percy Daggs III) and recent buddy Cindy (Mac) Mackenzie (Tina Majorino), all of whom have wound up at Hearst along with Veronica.

Other faces from the past pop up, too, but those are best left as surprises.

There are new characters, too, though, as well as new challenges - and, most of all, fresh mysteries.

On UPN, each season of "Veronica Mars" presented one year-long major mystery, flavored with other, smaller ones. For CW, as a way to welcome new viewers and make them comfortable, this new season of "Mars" is envisioned as three separate major mysteries, presented (should the series be renewed for the full season) in fan-friendly multiepisode arcs, as was the pioneering CBS series "Wiseguy."

The first mystery, which enters Veronica’s orbit near the end of tonight’s premiere, has to do with a campus serial rapist, who not only drugs and takes advantage of his victim (a fate Veronica herself suffered in the show’s initial season), but shears the hair from her head.

The investigation takes her, next week, to a campus sorority house, where she goes undercover during rush week at a "Stepford Wives"-feeling sorority, putting on a flowered print frock and her best flowing hairdo.

She arrives dressed to infiltrate - "dressed," she moans in one of her typically arch and quotable voiceovers, "like a ’50s vacuum ad."

Veronica and most of her friends are almost impossibly glib, but the dialogue is "Buffy" funny, not "Gilmore Girls" abrasive. Veronica, despite her fresh-faced appearance, is a very smart and savvy girl, just as "Veronica Mars" is a very smart and savvy show.

Both Veronicas, the character and the show, have spunk. And in their cases, I like spunk.