TORONTO -- After the massive success of her harrowing novel "Room," about a young boy held captive in a shed with his mother, Irish-Canadian author Emma Donoghue didn't want to write anything child-related.

"I just wanted a complete contrast," said the London, Ont.-based Dublin native, who won the Rogers Writers' Trust Fiction Prize and was a finalist for the Man Booker Prize and a Governor General's Literary Award for 2010's "Room."

But that changed during the research process for her new novel, "Frog Music," which is based on the true story of French burlesque dancer/prostitute Blanche Beunon and the murder of her cross-dressing female friend Jenny Bonnet in late 1800s San Francisco.

Donoghue discovered that during the inquest into the shooting death of Bonnet, Beunon claimed her estranged beau Arthur Deneve had taken her baby boy away and she didn't know where he was.

"I thought, 'Hang on, where is this baby?"' Donoghue explained in a telephone interview. "And it became clear the baby had not been living with them, the baby had been nursed out or farmed out, and I was fascinated with the notion that clearly they didn't much want this baby and yet here they were having a custody battle over it.

"So I decided that in a way the story would be kind of a double mystery -- first of all, who killed Jenny and what Jenny was like, sort of unpeeling Jenny's character like an onion. But then the kind of secondary storyline of not just where is Blanche's baby, but where is Blanche's motherhood?"

"Frog Music" begins with Bonnet's shooting in a room she and Beunon are renting in San Francisco. The story then shifts back and forth in time as it outlines events leading up to and following the murder during a sweltering August in 1876.

Beunon became a stage siren and landlord after moving to San Francisco from France with lover Deneve and their friend Ernest Girard, who all worked as circus artists in Paris.

She met scrappy Bonnet, a pistol-carrying vagrant who made a living catching frogs for restaurants, when the 27-year-old ran into her with her bicycle in the street.

The two appear complete opposites -- Beunon with her corsets and dresses, and Bonnet with her men's clothing that often got her fined or arrested (it was illegal for women to wear pants in public there at the time) -- but they form an unlikely bond that turns the burlesque star's life upside down.

"I see them each having different kind of wisdoms," said Donoghue.

"And I suppose one thing that really appealed to me about the storyline of this book is that I hadn't expected the baby plot to reel up like this."

Donoghue said she got the idea for "Frog Music" 15 years ago when she read a one-page summary on Bonnet in a piece on Victorian women called "Wild Women" by Autumn Stephens.

It wasn't until about four years ago that she started to write the story, drawing on about 60 newspaper articles as part of her heaps of research into the slew of characters, most of whom really existed. (Donoghue outlines all of her source material in the afterword, as she did with her 2012 short story collection "Astray.")

She discovered many myths built up around Bonnet, whose story has "never entirely disappeared," she said.

"I think she fascinates people, because it's not just that she got killed but that she lived as if she knew she was going to be killed.

"She lived at top speed so playfully and so recklessly. She was an attention-seeker of the highest order. You could tell that she had been a child actress, because she lived as if the city was her stage.

"I was just hooked as soon as I read about her."

As Donoghue explains, Bonnet was "an ahead-of-her-time character," cross-dressing "as if she wasn't remotely constrained by Victorian gender norms."

Meanwhile, Blanche seemed to be a pleasure-seeker who "thinks that she really likes this job" until Bonnet makes her question it.

"I knew it would be a bit of a risk, that somebody might start the book and go, 'Oh my God, Emma Donoghue seems to be celebrating the sex trade,"' said Donoghue. "But I just thought it made for a far more interesting story psychologically and ethically."

"Frog Music" is set against the backdrop of the smallpox epidemic and a city rife in racist attitudes toward its Chinese immigrants.

The story also touches on the tragedy of the so-called Industrial Schools and horrific conditions on "baby farms," where infants were sent by parents who were unable to take care of them.

"Those baby farms were real, but I researched them by looking at accounts of really bad orphanages today," said Donoghue. "So I looked at things like how would the children be stunted, the very interesting emotional shutdown that they have from literally not being picked up, and I looked a lot to see whether a child like that could recover."

Donoghue said she had "an academic knowledge of French" prior to writing the story and she frequently has her characters either speaking the language or singing it in real-life tunes.

The author has compiled those tunes into a songlist that she plans to post on

She said she's also fielding "a lot of interest in film rights" to the story.

Donoghue has already sold the film rights to "Room," which she said has entered the casting stage and could be in production later this year somewhere in North America.

Irish filmmaker Lenny Abrahamson will direct the script by Donoghue, who is also an executive producer.

"He wants to tell a very, very universal story with this book and I think the film is going to be just as good as the book," said the wordsmith, who is now writing a children's book.

"It's just very different, because even though it follows the book quite closely, in the film you'll get to literally see the mother directly whereas in the book you only get a glimpse of her through Jack. So I think it'll come across as much more the mother's film than the book was the mother's book."