In one of the first episodes of Hawai'i-based "Flight 29 Down," Kristy Wu's eternally good-natured character Melissa is goaded from her search for an all-important book of matches by a couple of fellow castaways, who chide her for being a drone.

Wu promptly runs into the surf, with clothes on, in a display of supposed spontaneity.

"Look!" she says, splashing about. "I'm fun! I'm spontaneous!"

Wu's work on the teen survival show doesn't announce itself in quite the same way, but the message is the same and the effect certainly more convincing.

"Flight 29 Down," co-produced by Rann and Gina Watumull's Hawaii Film Partners and series creators Stan Rogow and DJ MacHale, airs Saturdays on the Discovery Kids programming block on NBC. The half-hour show is shot entirely on location on O'ahu's North Shore.

Before "Flight 29 Down," Wu was best known for the serious roles she's played in a series of well-received indie films.

In "Face," which screened at the 2005 Louis Vuitton Hawaii International Film Festival, she played a child of rape who finds it difficult to reconcile with the mother who abandoned her.

In Gurinder Chadha's "What's Cooking?" Wu played a Vietnamese teenager whose relationship with a white boy conflicts with her parents' desire to retain their culture in a new country.

Wu also was around for the final episodes of "Buffy the Vampire Slayer," playing Chao-Ahn, one of several "potential" slayers activated for the show's final big battle.

In her latest film, "Cry Wolf," Wu plays one of a group of teens whose e-mail prank about a serial killer leads to real-life murder and mayhem.

"I do play dark, tortured roles a lot, so this role (as Melissa) is very, very different," Wu says. "It's a nice breath of fresh air."

Literally.

On a warm afternoon on the show's Mokule'ia set, Wu sits facing the same beach in which she immersed herself a season earlier, plugged in to her ever-present iPod, preparing for her next scene.

The second season has been running smoothly, thanks to fair weather (a heavy rain last season left the set submerged in three inches of water) and the cast members' familiarity with each other.

"It's like a continuation of where we left off last season," Wu says. "The biggest reason is that we all get along well, which leads to faster work days. We all knew what to expect."

Wu got her start with classical training in singing, piano and viola. Music eventually segued into acting as Wu got involved with school productions and, later, theatrical performances with Southern California's acclaimed South Coast Repertory Theater.

At Stanford, Wu majored in English, with concentrated studies in Mary Shelley and other authors, as well as children's literature. She also continued her work in theater, this time from behind the scenes.

Wu says she hopes to eventually incorporate her diverse background into work as a writer and director. In the meantime, she's open to opportunities in television and film.

"I find good in both media, but there are also projects that I'd rather not work on," she says.

"Every actor looks for a deep role with layers that people can identify with, just because of the way you play it."

Wu will get her wish in the show's second season and, she hopes, beyond.

MacHale, the show's writer and director, says Wu and her fellow actors on the ensemble show increasingly will be called on to explore the depths and complexity of their characters as "Flight 29 Down" continues to progress.

Reach Michael Tsai at mtsai@honoluluadvertiser.com.