Since she’s calling the tune, why not sing a few?

CARRIE FISHER is singing in the shower. Well, not in the shower, exactly; just in the bathroom. The reason? That’s where the piano is.

That there is an upright piano in Fisher’s bathroom is no more peculiar than anything else about her rambling 1930s manse in Beverly Hills, once home to Bette Davis. Decor-wise, the place is a Grimms’ fairy tale -- that is, if the Brothers Grimm had moonlighted as Hollywood comedy writers.

The winding, multitiered walkway to the front door is studded with signs that, taken out of their original context, feel like postcards from the edge: “Sea Plane Rides.” “Tunnel.” “No Vacancy.”

The grounds are peopled with garden gnomes, duck decoys and a multitude of other parallel life forms, including a living tree that, at second glance, has peering from its trunk a contorted face just like the ones on those bad-boy trees that hurl apples at Dorothy and the Scarecrow in “The Wizard of Oz.”

No, the peculiarity rests not in the bathroom setting but in the fact that Fisher is singing -- belting fragments of classic show tunes in a low, cigarette-smoky voice, rehearsing for the world premiere of her one-woman autobiographical show, “Wishful Drinking,” opening Wednesday at the Geffen Playhouse.

The show, which will predictably deal with Fisher’s well-publicized failed marriage, addictions, overdoses, mental illness and, of course, her best-known role as “Star Wars’ ” Princess Leia, will also be ... well, sort of a musical.

Fisher, who recently turned 50, cracks that singing “will give me a break from all the talking” but acknowledges that the inclusion of songs in her monologue holds special significance for the daughter of musical stars Eddie Fisher and Debbie Reynolds.

In recent years, Carrie Fisher -- screenwriter; author of four novels, including “Postcards From the Edge” and her most recent, “The Best Awful”; occasional script doctor; and a regular contributor of jokes for the Academy Awards -- has become more noted for her writing than her acting. But Fisher the singer is barely visible on the radar.

Actually, Reynolds, who lives nearby, is more excited about hearing her daughter sing than Fisher is about singing. “It’s been my dream for 50 years,” Reynolds says.

“I think she always felt intimidated, because Eddie was singing and I was singing -- of course, Eddie left when Carrie was 2, but his reputation was there; his songs were on the radio,” observes Reynolds in a separate conversation. “She used to sing as a little girl, but then it just stopped. She didn’t want to sing in public anymore. But she certainly has a great gift.”

Fisher admits: “I always had a lot of fear. When I was a kid and went onstage and sang, I used to be such a perfectionist that it just destroyed me.” That’s why she stumbled into movie acting rather than musical theater. Showbiz was in her blood, but “I did not get into that thing where you go flat out into what your parents do.”

Much like the signs leading to her house, the old songs will acquire new meaning by virtue of the context. For example, a lyric from “West Side Story’s” “A Boy Like That / I Have a Love” -- “Stick to your own kind” -- is sung in reference to Fisher’s failed relationship with Creative Artists Agency managing director Bryan Lourd, the father of Fisher’s 14-year-old daughter, Billie, who left Fisher for a man.

Of course, that song may or may not be in the show. At this early rehearsal, surrounded by shower, tub and sink, all is yet to be determined. The show, written by Fisher, will have plenty of songs, but its director, Josh Ravetch, frets seemingly to anyone who will listen: “We still don’t have an opener.”

Pianist Jerry Sternbach -- who can play any show tune on request and, speaking of Broadway, thinks the new “Chorus Line” can’t possibly match the original magic -- marvels at the room’s superior acoustics. Fisher has nurtured the career of pop musician James Blunt, who once worked on his songs at this very piano. Sternbach will accompany Fisher onstage.

Also present in the chamber are Fisher’s assistant and co-producer, Kim Painter, and Fisher’s two small, fluffy dogs, Dwight and the Dalai Lama, who waddle in and out on short legs. Oh, yes, and singer Rickie Lee Jones (“Chuck E.’s in Love”), a friend who just happened to stop by but was drawn to the sound of music like a pop-diva moth to the flame.

One Western boot beating rhythm on the terra cotta tile, Jones offers soulful snatches of a few tunes she thinks might be great for the show. Fisher collapses to the floor in mock distress. “I can’t sing that -- it’s too ‘range-y’ ” she pleads as Jones’ piercing voice rockets up the scale.

But in a conversation in her spacious backyard after the rehearsal, Fisher says she’s game to let it all hang out, musically and emotionally. This may come as no surprise to readers of her novels, which have offered fictionalized versions of her real-life travails.

But this time, for the first time, Fisher says, she’s telling her own story with her real name attached. And why not, she reasons. It’s all out there anyway.

“It was in the paper when I went into a mental hospital, which is part of the reason I ‘came out,’ ” says Fisher, who has made something of a second career out of lecturing about her fight with bipolar depression. “I was in rehab twice -- once because of what they put into my system at the mental hospital, and once because of what I put into my system myself.” Alcohol was never her substance of choice: “I was a wishful drinker in the sense that I wished drinking worked for me,” she says.

The show, she says, “is me controlling the information. It’s like walking into a room and before someone can say: ‘You’re fat,’ you say: ‘OK, I’ve put on 10 pounds.’ ”

Continuing, with appropriately placed expletives, Fisher says: “I’ll always be known as ... Princess Leia. OK. Whatever. I don’t ever escape ... Hollywood. I could go to ... Saudi Arabia and it’s going to be there because I’m there.”

And it’s all good with Fisher -- as long as it’s funny. “If my life wasn’t funny, it would just be true, and that’s unacceptable. My brain looks at things funny.

“For a long time, I’ve known people who have taken all the charm and romance out of self-pity,” she adds. “That is of no interest to me.”

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diane.haithman@latimes .com

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‘Wishful Drinking’

Where: Geffen Playhouse, 10886 Le Conte Ave., Westwood

When: Opens Wednesday. 7:30 p.m. Tuesdays through Thursdays, 8 p.m. Fridays, 4 and 8:30 p.m. Saturdays, 2 and 7 p.m. Sundays

Ends: Dec. 23

Price: $35 to $69

Contact: (310) 208-5454