Whether it’s post-9/11 jitters or millennial aftershocks, TV producers are fascinated by the ideas of "What if ?," "If only ..." and "There but for the grace ... ." Last season saw a drama — ABC’s "That Was Then" — and a comedy — The WB’s "Do Over" — in which thirtyish men were allowed to relive their ’80s adolescence.

This year is all about the girls. On Showtime’s "Dead Like Me," an 18-year-old (Ellen Muth) becomes a grim reaper, taking souls while trying to reconnect with her troubled family. On CBS’ "Joan of Arcadia," a high-schooler (Amber Tamblyn) talks to God, who gives her puzzling missions that have far-reaching effects on her friends and troubled family.

On Fox’s upcoming "Wonderfalls" (created by Bryan Fuller, who also created "Dead Like Me"), an apathetic 20-something (Caroline Dhavernas) gets cryptic messages from talking gift-shop tchotchkes, which cause her to alter the lives of those around her (including friends and troubled family).

There seems to be a theme here.

Now, starting Thursday, Oct. 30, there’s FOX’s "Tru Calling," starring Eliza Dushku ("Buffy the Vampire Slayer"). She’s not talking to God, as near as we can tell. Instead, she’s talking to the dead, or, to be more accurate, the dead are talking to her. They want her help. They want not to be dead. Luckily for them, Tru’s just the girl to ask.

After displaying some possibly psychic powers at 12 during the funeral of her mother, who was murdered in front of her, Tru wakes up as a 22-year-old college grad and discovers she has gone back one day in time. She then tries to help her self-destructive brother (Shawn Reaves), coke-sniffing sister (Jessica Collins) and the slain corpse that spoke to her during her first night as a morgue attendant.

Created by Jon Harmon Feldman ("Dawson’s Creek," "American Dreams"), "Tru Calling" posits a situation with massive theological implications (but they don’t really go there) and enough time-travel conundrums to give H.G. Wells a tension headache.

According to Feldman and fellow executive producer Dawn Parouse, Tru alone has this power. There was another, but that person is dead. "There’s a mythology that backs that up," Parouse says. "It’s no mystery that she wound up at that morgue."

"I don’t think she chose it," Dushku says, "or if she did, she doesn’t know it."

The producers also acknowledge the effect of recent events. "Look," says Feldman, "9/11 is part of the collective consciousness right now of our country. ’If you could do things differently ... .’ You can’t help but access that in the writing at this subconscious level. Why is the sense of changing things in the air ? That’s probably a real good reason."

"When you say 9/11," Parouse adds, "I thought it was real important for her to just be your average 22-year-old girl, because everybody did feel that. ’What if I could have done something ? If only ... .’"

While 9/11 may be partly responsible for some current shows, the idea of changing history is as old as storytelling, and is a TV staple.

From 1996 to 2000, Kyle Chandler starred in "Early Edition" as a stockbroker given the next day’s Chicago Sun-Times so he could change the headlines (a job he inherited, along with a cat, when the previous recipient died).

Even earlier, from 1989 to 1993, "Quantum Leap" starred Scott Bakula as a scientist thrown into the bodies of people at different points in history. He was then stuck there until he "put things right that once went wrong" to the satisfaction of a seemingly omniscient computer, Ziggy.

These shows throw a monkey wrench into the idea of absolute predestination, since someone wants to undo something that’s already happened, but wasn’t meant to.

Maybe people die that shouldn’t have.

"Absolutely," Feldman says.

"Absolutely," Parouse concurs, "and maybe there’s someone to right the wrong."

"And if there’s someone to right the wrong," Feldman continues, "what we’re going to explore in this series is, if there’s someone there to prevent death, maybe there’s someone there to ensure death. That’s something we’re going to go through as well."

"And maybe he’s going to be a hot 22-year-old guy," Parouse says.

Unfortunately for Tru, she doesn’t have the Almighty making cameo appearances, nor talking wax lions, nor a newspaper with constantly shifting headlines, nor Ziggy. She has only her own wits.

"She’s not a superhero," Dushku says. "She’s going to have triumphs, where she can save people, and she’s going to have really painful experiences where she just can’t, and she’s going to deal with that."

Dushku reportedly passed on a "Buffy" spinoff featuring her character, the rogue slayer Faith, for "Tru Calling," but the concepts are not that far apart. A slayer is a girl chosen — either randomly or by design — to save the world from evil. Tru has been chosen to save, not the world, but one life at a time.

Whether or not "Tru Calling" becomes anything like a meaningful metaphor for salvation and redemption, the thought that second chances are possible is seductive.

"In the world we live in now," Feldman says, "there’s this level of helplessness that people feel. How can you change things ? How can you make it better ? How can you prevent all this needless death and destruction ?"

"It’s just the hope," Parouse says, "that comes with saying, ’Maybe not everyone that dies should be dead.’ Wouldn’t it be nice if that were true ?"