8-9 p.m. Monday, Sept. 24

The Invasion of the Geeks starts Monday with the arrival of two new series in which smart but socially backward young men are pushed out of their intellectual shells by unforeseen events. CBS launches the half-hour sitcom "The Big Bang Theory," about a beauty who moves across the hall from two geeks. NBC, on the other hand, has "Chuck," who accidentally enters the world of cloaks and daggers. It's a smart mix of comedy, sex and danger and a perfect building block for NBC.

The "Chuck" pilot, from "The O.C.'s" Josh Schwartz and his film-school classmate, Chris Fedak, is one hour of nonstop action and fun that pumps new energy into a popular theme (Spider-Man, anyone?). The second episode, also sent for review, captures some of the magic and all of the action but smoothes over some of the more entertaining rough edges, costing the show some of its edge-of-your-seat quality.

A particularly well-cast show, "Chuck" stars Zachary Levi as the leader of the Nerd Herd at Buy More electronics (Geek Squad at Best Buy, only without the trademark infringement). Amiably bland, Chuck hasn't had a social life since his former college roommate stole his girlfriend. Since then, it's been looking like a long and single life.

Meanwhile, that former roommate became a rogue CIA agent who, in his dying moments, sent an e-mail to Chuck that exposed his brain to all of the nation's secrets. That makes Chuck a valuable property for both the CIA, represented by sexy and deadly Sarah Walker (Australia's Yvonne Strahovski), and the National Security Agency, repped by brutal and tough John Casey (Adam Baldwin).

Further complicating things is that Chuck is no human computer. Secrets come to him randomly and uncontrollably, though always in the nick of time to save the day.

The pilot is full of dark, dangerous and sexy moments, but in the second episode, Sarah gets an undercover job serving fast-food wieners and John joins the Nerd Herd at Buy More. Both situations are rife with comic potential, but now Sarah seems less lethal and John less explosively violent. Levi, Strahovski and Baldwin are fun to watch in every scene, but for Strahovski in particular, the series becomes a showcase that lets her go from cute to deadly in seconds.

A successful "Chuck" also will raise the profile of Joshua Gomez, who plays Chuck's best pal, dorky but hopeful Morgan, adding dollops of comic relief every time he steps into a scene.

"Chuck" confidently leads off a promising sci-fi/fantasy-themed lineup, followed by "Heroes" and newcomer "Journeyman." There is formidable competition (especially from CBS' comedies and ABC's "Dancing With the Stars"), but as the cheers at Comic Con suggested, there is a big appetite for a show like this.

College Hill Pictures and Wonderland Sound & Vision in association with Warner Bros. Television
Executive producers: Josh Schwartz, McG
Co-executive producers: Peter Johnson, Chris Fedak
Producer: Paul Marks
Co-producers: Ben Kunde, Lisa Cochran-Neilan
Diector: McG
Teleplay: Josh Schwartz, Chris Fedak
Director of photography: Ramsey Nickell
Production designer: Cecele Destefano
Editor: Norman Buckley
Music: Tim Jones
Set decorator: Cindy Lewis
Casting: Patrick J. Rush
Chuck Bartowski: Zachary Levi
Sarah Walker: Yvonne Strahovski
John Casey: Adam Baldwin
Morgan Grimes: Joshua Gomez
Ellie Bartowski: Sarah Lancaster
Captain Awesome: Ryan McPartlin
Bryce Larkin: Matthew Bomer