"It's so rare to find a part that is so much fun, that feels so much like me," enthused Henner during a recent, prerehearsal chat. "She's funny, she's sexy, she's outrageous, she's outspoken, she likes to stir the pot - she's like the Cat in the Hat. She comes into these people's lives. It's just a wonderful character."
It's such a great part for Henner that this is the third time she's tackled it. But this time around, she had some new incentives to take the gig.
First, it finally gave her a chance to work with producer Jed Bernstein, the Broadway mahoff who has staged such Great White Way presentations as "Oleanna, "Hair," "Driving Miss Daisy" and "Equus."
"Jed and I have known each other for years, from when I was doing 'Chicago' on Broadway," said the Chicago native, who is 61 but looks at least 10 years younger. "We've just always run into each other over the years, and we always said, 'We've got to do something together.'
"When he first got involved with [Bucks County Playhouse], he said, 'I'm going to be doing this, I want you to come up here some time.' I said, 'Great. I'm in.' And when this opportunity came up, I thought, I have to do this."
Geography also figured in her decision to take the job.
"I fell in love with Bucks County when I came here for Christmas 2000 with my family," she explained. "I was performing in the national company of 'Annie Get Your Gun,' and I was about to open in Philadelphia. So we came here and took over a bed-and-breakfast for the holidays."
Yet another lure was the chance to work with Mason, whom she described as an acting role model.
"I remember the first time I saw Marsha [perform]," recalled Henner, who hosts a daily lifestyle-advice Internet talk show (8 to 11 a.m., gnclive.com/programs). "I went crazy for her.
"We met on July 7, 2001 - which was a Saturday. I saw her in 'The Cherry Orchard' in Santa Fe [N.M.]."
Yes, Henner remembers the exact day she and Mason met. That's because she is one of a handful of people worldwide scientifically proven to have a condition called hyperthymesia. As such, she can recall with clarity virtually every day of her life.
"People say, 'It's a gift,' and I say, it's a gift until I have to do a show I've already done and I remember how I did it the first time," she said.
"With this piece, the character's like me anyway, so I'm always gonna use that as a base. And your performance is always informed by the other actors onstage with you, and what they bring to it and the relationships they have.
"So, there is that kind of undoing, of trying to undo knowing your lines. You don't just go up there and start doing them."
Her rare ability has led to yet another career for Henner: She consults for the CBS-TV crime drama "Unforgettable," which stars Poppy Montgomery as a cop with a Henner-esque memory.
"I give them a lot of story ideas and read all the scripts and check them out to make sure they are being authentic to what the gift is." she said.
And in her spare time, Henner tours a one-woman show called "A Memorable Evening with Marilu Henner," during which she talks about her life and career and even sings a few songs.
So with all the hats she wears, why does she even bother with live theater?
"It's been part of me since I was a tiny little child," she noted. "Since I was 2 years old and got onstage the first time, I knew I wanted to act."
Bucks County Playhouse, 70 Main St., New Hope, 8 p.m. Friday, 4 and 8 p.m. Saturday, 2 p.m. Sunday, 7 p.m. Tuesday, 4 p.m. Wednesday, 2:30 and 8 p.m. Thursday, $57.50, $39 and $29, 215-862-2121, bcphtheater.org.