Where: Theaters everywhere.

When: Opens today.

Rating: PG-13 for some sexual content.

Running time: 98 minutes.

Bottom line: Reese Witherspoon's charm enlivens this romantic comedy with a supernatural spin.

Romantic comedy is one of Hollywood's most enduring formulas - get two people together, throw up an obstacle to keep them apart, overcome that obstacle in the final reel, end with a kiss. Success or failure depends on the variables: How appealing are the people, how big is the obstacle and how sincere is the emotion required to remove that obstacle?

"Just Like Heaven" succeeds on all three counts, thanks to a funny script, well-executed direction by Mark Waters ("Mean Girls") and the boundless charm of star Reese Witherspoon.

Witherspoon plays Elizabeth, an overworked young San Francisco doctor with no social life. One night, on her way to a blind date set up by her married-with-kids sister Abby (Dina Waters), Elizabeth is involved in a car crash - the outcome of which is left murky for the time being.

The movie flash-forwards three months, as the morose David (Mark Ruffalo) sublets Elizabeth's old apartment. All of Elizabeth's furniture and decor is there, and apparently so is Elizabeth, who is none too happy about the slob occupying her home and leaving water rings on the coffee table. Elizabeth has other problems - like not having a physical presence or remembering her past life - and David is reluctantly enlisted in helping her rediscover who she is and what happened to her body.

The script - by veterans Peter Tolan ("Analyze This") and Leslie Dixon ("Freaky Friday," also directed by Mark Waters), based on a novel by French author Marc Levy - is filled with frothy humor. But there's a serious undercurrent running between Elizabeth and David, two people who have (for reasons revealed as the story unfolds) put their lives on hold for too long.

Witherspoon provides whip-smart comic timing and a bubbly charm that makes you love Elizabeth even when she's being Felix Unger to Ruffalo's Oscar Madison. Ruffalo, who is usually too brooding for this kind of material (e.g. "13 Going on 30"), turns out to be perfect here because his character does brood a lot. And Donal Logue ("Grounded for Life") and Jon Heder, the star of "Napoleon Dynamite" and the pride of Brigham Young University, give hilarious supporting turns.

Waters manages the minor miracle of taking these tried-and-true romantic-comedy elements and making them seem fresh. "Just Like Heaven" isn't completely heavenly - particularly toward the finale - but the pairing of Witherspoon and Ruffalo makes it pretty close.

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