Get ready, mystery nuts: Agatha Christie, who was once dubbed "the world's best-selling author" by the Guinness Book of World Records, is primed to make a big comeback. On Monday, Christie's estate signed with talent agency William Morris Endeavor (WME) to develop new adaptations of the author's work for film, television, and digital media.

In the near-century since Christie's first piece was published, her dozens of novels, short stories, and plays have sold billions of copies, which makes her — from a sales perspective — the most successful female writer of all time. But the success of Christie's work hasn't inspired the same sustained media interest as that of fellow British authors Jane Austen and Charlotte Bronte, for example. Bronte's Jane Eyre has seen numerous big-screen adaptations (the most recent was released in 2011), and Austen's work has inspired everything from devout adaptations (including the Keira Knightley-starring version of Pride & Prejudice) to playful twists on her original stories (Clueless, which is loosely based on Emma, and From Prada to Nada, which draws inspiration from Sense and Sensibility.) Though her characters and stories have stayed alive through a repetitive series of films on British television, Agatha Christie's impact has waned.

That wasn't always the case. The first successful Christie adaptation came in 1957, when Billy Wilder helmed the multiple-Oscar-nominated Witness for the Prosecution. Over the next 30 years, Christie heroes like Miss Marple and Hercule Poirot appeared in multiple movies, played by the likes of Margaret Rutherford, Albert Finney, and Peter Ustinov. The Poirot adaptations were particularly successful, leading to a massive box-office gross for 1974's Murder on the Orient Express and Oscar wins for 1978's Death on the Nile. But Ustinov's final appearance as Poirot in 1988's Appointment with Death became an unwitting, ironic death sentence for Christie on the silver screen. After Ten Little Indians the following year, Hollywood forgot about her, and it hasn't remembered her until now.

The blackout on Agatha Christie adaptations has been as much Hollywood's loss as Christie's, because the author's oeuvre is a model of something American film has struggled for decades to find: A female creator that offers progressive views about women young and old. Women had barely earned the right to vote when Christie first made waves as a writer, disseminating what scholar Roberta S. Klein describes as "unconscious, intuitive feminism." Thankfully, Christie's first publisher, John Lane, insisted that she be published under her own name, rather than take on a male pseudonym. Poirot might have dominated her pen, with appearances in more than 30 of Christie's titles, but Miss Jane Marple and Mrs. Tuppence Beresford balanced out her masculine hero by offering fierce and capable female detectives unrivaled in comparable stories of their time.

Christie's women
Miss Marple was introduced in a series of stories that began with 1926's "The Tuesday Night Club" as an old knitter who easily solved mysteries while obsessing about dropped stitches. When she appeared in her first novel, 1930's The Murder at the Vicarage, she was described as the "nasty old cat" who always snooped on her neighbors, and an old and knowledgeable woman patronizing the young. 

Over time, though, Christie reshaped Marple from the cliche of a gossiping old woman into a weathered heroine with great instincts. Gossip isn't a means for Marple's pettiness, but a way that she — as an oft-ignored older woman — gathers information to make amateur (but accurate) deductions. In her subsequent appearances, Marple becomes softer and kinder, but no less intelligent, and educated in a diverse stable of subjects. When Margaret Rutherford portrayed Marple in 1962's Murder, She Said, the big-screen potential of a Marple-type character, the fiercely intelligent older woman, became clear. The motif suits talented actresses — both British and American — including Helen Mirren, Judi Dench, Glenn Close, and Candice Bergen, who too rarely have a chance at great starring roles.

Despite Miss Marple's proven track record, though, it is Christie's almost forgotten heroine — the plain-Jane but dynamic Tuppence Beresford — who holds the most promise for the silver screen. Tuppence Beresford was Christie's first female sleuther, appearing in Christie's second book (The Secret Adversary) alongside her future husband Tommy. When the pair reunites in post-WWI Britain, it is Tuppence who decides that they should become "Young Adventurers," selling their talents under the motto "no unreasonable offer refused." They quickly find themselves in the middle of a mysterious disappearance, sleuthing and getting into trouble in their quest to make careers for themselves.

Unlike Marple, Tuppence regularly scowls at any reference to female stereotype. She's a go-getter who pays no mind to a lady's place. She outwardly questions assertions that she must be looked after by Tommy, or that she's weak or flighty. In a moment that recalls strong female heroines like Maya in the Oscar-nominated Zero Dark Thirty, Tuppence remarks: "Do I look like the sort of girl that's always falling in love with every man she meets?" Tuppence is Christie's feminist heroine, sparring with an "old misogynist" who calls her a minx, and acting as an equal partner to Tommy. And as the only detective Christie wrote that aged alongside her creator, Tuppence could be faithfully captured by any capable actress over the age of 20 — from Jennifer Lawrence to Kerry Washington to Allison Janney.

Hollywood's Agatha Christie revival 
The opportunities afforded by the union between WME and the Christie estate are limitless, but this isn't the first time a major studio has attempted to revive Christie for modern audiences. Just two years ago, Disney almost signed a deal that would have seen 39-year-old Jennifer Garner play Miss Marple. In Hollywood's typically ageist tradition, Disney wanted to make the elderly spinster younger and more contemporary — but, after a day's worth of near-universal internet scorn directed at the project, the deal was killed. The ill-formed plan is a cautionary tale that exemplifies the dangers in adapting Christie's work today. So many Hollywood adaptations wrongfully make formidable female protagonists younger and meeker for the big screen. Lisbeth Salander was made to be softer and more vulnerable for the U.S. remake of Girl with the Dragon Tattoo, and Jane Eyre has repeatedly been enfeebled on-screen. Tuppence Beresford has also been marginalized herself, in a 1983 miniseries about the couple: After solving the crime, Tommy takes most of the credit, rather than fairly sharing the spotlight with his partner.

The key to a truly successful Christie adaptation is to revel in the power of these women as detectives. Marple might tend to her garden and go to tea, and Tuppence might have been conceived in post-World War I angst, but either character could easily be dropped into the modern world and keep all the magic they possessed decades ago. It isn't hard to imagine Tuppence as a hacker, itching to get out and see the world outside of the internet — or to see Marple leave the Best Exotic Marigold Hotel to have a sleuthing adventure.

WME's deal with the Christie estate could not be timelier. Danny Boyle recently spoke about the lack of great female roles, marking the latest in the chorus of Hollywood heavyweights speaking out about the imbalance. Kristin Scott Thomas now works more in France, where they're "less afraid of older women" over 50 than in Hollywood. And of course, Veronica Mars made Kickstarter history, carrying Christie's proud tradition of female sleuths into modern day. Age diversity, strength, and dynamic women — Agatha Christie offers it all, if Hollywood has the wisdom to honor her properly.

Girls on Film is a weekly column focusing on women and cinema. It can be found at every Friday morning. And be sure to follow the Girls on Film Twitter feed for additional femme-con.