Nixon has had quite a life, and her book, co-written with Stephen Cole, is utterly delicious. Renowned as the “singing voice” of Margaret O’Brien, Natalie Wood, Deborah Kerr, Rita Moreno, and especially Audrey Hepburn, Nixon has forged a career as an opera, musical theater, and concert artist that has included working with composer Igor Stravinsky and at the Disney Studios, as well as with gay composers such as Leonard Bernstein and Aaron Copland.

Open “I Could have Sung All Night” to any chapter and savor the gems of this extraordinary performer’s career. She begins by discussing the honors she received when the fully restored “The King and I” was shown in Hollywood. Nixon, of course, dubbed not only its star, Deborah Kerr (whom Nixon reveals was having an affair with Yul Brynner at the time), but also Rita Moreno, the film’s Tuptim. She appeared in the ensembles of many movie musicals. Sadly, a filmography isn’t included.

Her second husband was composer Ernest Gold, composer of the score for the movie “Exodus.” The renowned gay pianist and performer Liberace helped her develop her stage personality, and Victor Borge taught her how to handle comedy.

Of course, what everyone wants to know is the dirt about dubbing all those women. Truth be told, there isn’t much. Nixon got on well and remained lifelong friends with them. She reveals that Audrey Hepburn was saddened that she wouldn’t be doing her own singing, because producer Alan Jay Lerner wouldn’t allow it. However, there are moments in the movie when the song track is a combination of both Hepburn and Nixon.

When she first met Julie Andrews on the set of “The Sound of Music” — Nixon plays Sister Sophia — the cast and crew expected a cat fight. Instead, Andrews was gracious and they became fast friends.

On stage, Marni Nixon has played the leads in “The King and I” (as Anna Leonowens), “The Sound of Music” (as Maria von Trapp), and “My Fair Lady” (as Eliza Doolittle). She is heard as the voice of Grandmother Fa in the animation classic “Mulan,” and has appeared on TV’s “Law & Order SVU.”

Nixon’s smart enough to know that gay men helped make her the star she is today, and she writes appreciatively of their support.

She has survived breast cancer, and currently teaches master classes. While she’s eased her career commitments as she’s aged, Nixon’s now deeply involved with her family, especially her grandchildren.

Co-written with gay writer, Stephen Cole, whose work includes the upcoming musical, “The Night of the Hunter,” there’s no doubt that “I Could Have Sung All Night” is a book to sit back, relax and savor as the treat it is, even if you are not in a bathtub.