Robert Stack frets that a serial crime may be in the works.

His "Unsolved Mysteries" was axed by NBC last year after nine seasons, but gets another chance on CBS beginning tonight at 8 onCh. 2. Will viewers find the series on a new network, he wonders, or will it fall victim to cancellation a second time?

Stack returns as the guide to real-life stories of trouble that often find endings with help from viewers.

And that's why the actor - whose authoritarian voice can evoke images of bench warrants bearing your name - wants to see "Unsolved Mysteries" survive.

"Without being a Pollyanna, I feel an obligation to fulfill the potential of the show," Stack says. "It functions on the level of the audience making it work, making the calls, catching the dirty rats, bringing the families together."

Hard to believe anyone, even mighty NBC, would cross Eliot Ness and his fans. It was as the tough G-man in the series "The Untouchables" that Stack gained his first TV fame - and learned a lesson about Hollywood.

Naysayers warned Stack off the drama, saying, "What do you do after you catch Capone? It's never going to work." Yet the show ran from 1959 to '63.

Not much has changed. Stack recalls doing a promo for a struggling sitcom that then-NBC programming head Brandon Tartikoff considered "too ethnic and too New York and probably wasn't going to make it."

The show was "Seinfeld." Go figure.

"It's like striking oil in a wildcat well; you have no idea what's going to work," Stack says. He figures "Mysteries" was doing well enough for NBC but claims no beef with the network over the cancellation.

He's clearly hoping viewers want more, though.

"Some of the shows dumped by NBC, like `JAG,' are picked up by CBS and they're a smash," Stack notes. "It's Russian roulette."

He makes the comment lightly; in conversation, it turns out, he's much more jovial and relaxed than his screen image.

At 79, Stack is well-versed in the mysteries of Hollywood and show business in general. His great-grandfather opened one of the first theaters in Los Angeles, and his grandparents, uncle and mother were opera singers.

"My mother married the only Irishman in County Kerry who couldn't sing - and that's whose singing voice I got," Stack says.

Believing there had to be some ability "hiding under there," his mom signed Stack up for lessons with the voice coach of actress-singer Deanna Durbin.

The teacher figured a little exposure to Durbin's talent would benefit Stack and took him to Universal Studios to see her. Producer Joe Pasternak quickly spotted the handsome 20-year-old.

"How would you like to be in pictures?" Pasternak asked, offering a screen test.

The job turned out to be opposite Durbin in 1939's "First Love," and Stack had the much-publicized honor of bestowing her first screen kiss. He also was introduced to moviedom's pecking order.

As the film's star, Durbin had the luxury of a work day that ended at 6 p.m. That left Stack to do his closeups without her; a chalk mark on a blackboard was to serve instead, director Henry Koster told him.

"I began to look a little cross-eyed," the actor recalls. "Later, one of the reviews said Robert Stack showed great promise, even to the fact his eyes seemed to change focus when he looked at Deanna Durbin."

Stack, eventually skillful enough to gain a best supporting actor Oscar bid for 1957's "Written on the Wind," chuckles at that long-ago notice. He allows that he doesn't try to take things too seriously.

"It's all malarky. Even the wonderful part is malarky."