"Not a dream! Not a hoax! Not an imaginary story!" Those words used to appear on the covers of Superman comic books.

They became necessary because the writers, desperate for new ideas, began to write stories in which Superman was dying, or in which Clark Kent became Batman, or where Lois Lane, not Clark Kent, had superpowers. They called these stories "imaginary stories."

So, when the writers really wanted to make a major change in the Superman mythos, they had to tell the reader that this was not an imaginary story.

Most of the TV shows I watch regularly need to tell the reader what is and what is not an imaginary story.

Years ago in this column, I complained when an entire season of Witchblade turned out to be an imaginary story. Of course, Dallas did it first. On a recent episode of Smallville, when Clark Kent reveals his identity to the world, you know it is, in some sense, an imaginary story. In the end, Clark fixes it with time-travel, saying, for what must be at least the third time on Smallville, you can change the past just this once, but never again.

spoiler warning

On Terminator – the Sarah Connor Chronicles, probably my favorite show on television, (now gone, alas) John Connor (SPOILER WARNING) travels to the future, only to discover that nobody there has ever heard of him. There the story ends, and the next movie will follow a different timeline. Which makes the entire series, Terminator – the Sarah Connor Chronicles, an imaginary story.

On Lost, it seems as if everybody has sprung loose in time, and the only rationale necessary for anything to happen is "The Island wants it to happen." Some Island! But at least (or so we're told) it is "Not an imaginary story!" As two recent story titles have told us, "What Happened, Happened." and "Dead is Dead". Nothing can change the past. I like that. And I'll believe it when I find out how they are going to dig themselves out of all the plot holes they've dug themselves into.

And don't get me started on Heroes, where it seems everything that happens is either a dream, a hoax, or an imaginary story -- or all three at once. Some say that Heroes, like Smallville, has blown up the refrigerator. I still have hope. Is there a script doctor in the house?

The only series I follow regularly that has not used time travel is Dollhouse, which just keeps on getting stranger. As one of the characters says, "We're pimps and killers for hire, but in a good way." I don't know how Joss Whedon does it, but somehow he can have his characters do evil things and remain sympathetic. Case in point: Jayne on Firefly. In Dollhouse everybody does evil things. The dolls can't help themselves, and the motives of the people who work in the dollhouse are obscure. Even the ex-FBI agent is willing to date-rape a doll to preserve his cover. I'm not sure series television is ready for this much moral ambiguity, not to mention this complex a plot.

The ratings of Dollhouse have not been any better than the ratings of Terminator, but the network seems to be willing to cut Joss Whedon some slack, so the show may return in the Fall. But the last episode of Season One of Dollhouse will not be shown on television. You'll have to wait for the DVD.