On this particular evening, Betty is enrapt in Love while Del, who doesn't realize she's in the house, does some dirty business in the living room. It goes down bad, and Betty, peeking out from behind a door, watches in horror as Del is murdered by philosophizing hitman Charlie (Morgan Freeman: Deep Impact, Amistad) and his half-cocked apprentice, Wesley (Chris Rock: Dogma, Lethal Weapon 4).

We all have the little touchstones of reverie that get us through our mundane workaday days, enabling us to endure the awful prosaicness of routine. Betty's is her imaginary affair with "Dr. David Ravell" (Greg Kinnear: As Good as It Gets), one of A Reason to Love's leading men... and Del's murder pushes her so deeply into this consoling fantasy that she now believes she is Nurse Betty, who dumped David at the altar six years earlier on the soap. Convinced she has to win "David" back, Betty hops in a Buick borrowed from Del's car lot and heads for California.

There's a lot of very wry, dryly humorous stuff here: the clips from A Reason To Love that are just barely more absurd than real soap operas; Kinnear sending himself up again, much as he did in Mystery Men, using his movie-star good looks to create a self-involved Hollywood monster; and Betty's utter faith in figments of her own imagination, so sweetly serious that it's hard to see how anyone but girl-next-door Zellweger could have pulled off so challenging a role. Her Betty is so sympathetic that though we can laugh at her unwitting pranks, she never becomes an object of outright ridicule.

Like a millennial Wizard of Oz, Nurse Betty is about the power of an all-consuming fantasy to help us cope with life's disasters. Alternately startling and funny, melancholy and bizarre, this ardently black comedy is nevertheless the most lighthearted work yet from director Neil LaBute, whose previous films are the grimly misanthropic In the Company of Men and Your Friends And Neighbors. (Notably, LaBute did not write Betty's screenplay, as he did with his previous films -- this deliciously clever script is the work of John C. Richards and James Flamberg.) Unlike Dorothy's, however, Betty's odyssey is more about using the comforts of home -- or lack thereof -- as the jumping-off point for bigger things. There are places better than home for Betty.

Those better places are the ones we all dream about, the ones that TV and movies incite the desire in us to see and experience. Betty encounters a barmaid, on her trip West, who says she once went to Rome because of Audrey Hepburn in Roman Holiday. And Betty wants the world she sees on A Reason to Love, one in which you can see the ocean and the mountains, one that's sunny and full of palm trees. And, in the slightly off-kilter world of Nurse Betty, she can have it: one character tells her that very description covers all of Southern California.

But how healthy are these everyday kinds of fantasies, the ones in which we all indulge? Nurse Betty casts a skeptical eye at them, and knows that while daydreams may prompt us to look for something more, we also risk disillusionment when reality doesn't measure up. Betty -- or her alter ego Nurse Betty -- is in love with a picture (watch how she treats the life-size, cardboard-cutout David, a birthday gift from friends, even before she enters Candyland) and an invented character in David, and as long as she can maintain unreality, she's fine. And when Charlie and Wesley set off after Betty -- what they wanted from Del just happens to be in the trunk of that Buick -- Charlie finds himself becoming entranced with the Betty he sees in a photo he scammed from her friends and with the Betty he creates in his mind, the "cunning, ruthless woman" he imagines her to be. Their illusions get them through tough times -- Betty's trauma and Charlie's impending retirement -- but the loss of those dreams is a crushing one.

But, as befits a Wizard of Oz update for our simultaneously hopeful and cynical times, disappointment is recycled into yet another fresh start. Warmly quirky, thought-provoking and silly, Nurse Betty won't provoke you to abandon your daydreams, but it might inspire you to look a little askance at them.