Why is Wonder Woman an Amazon? Deleted 'Professor Marston' scene reveals key biographical detail. (Exclusive)

Last year may have been the year of Wonder Woman, but the Amazon warrior’s big-screen box-office might in her solo adventure as well as in the team-up adventure Justice League sadly didn’t aid Professor Marston and the Wonder Women, Angela Robinson’s underseen biographical drama. Premiering at the Toronto International Film Festival, the film tells the unconventional love story of the DC Comics titan’s real-life parents, psychologist William Moultan Marston (Luke Evans), his wife, Elizabeth (Rebecca Hall), and their mutual partner, Olive (Bella Heathcote). Yahoo Entertainment exclusively premieres a deleted scene from Professor Marston which earned a spot on our Best of 2017 list that explains a key piece of Wonder Woman’s origin story.

In a framing device that brackets the movie, Marston is subjected to a pointed interview with Josette Frank (Connie Britton), a member of the Child Study Association of America, which is exploring some of the subtle (and not so subtle) psychological messaging that Wonder Woman’s creators included in her supposedly kid-friendly comics. For this particular scene, she’s interested in hearing why Marston chose to make his heroine an Amazon. “In Greek mythology, Amazons were a powerful tribe of women who lived without men,” the ex-professor explains to his skeptical interrogator. “It is important to me that young girls of today realize they have the power within themselves to create their own destiny. To be president of the United States if they want.” Not surprisingly, he’s less willing to opine on why her signature catchphrase is “Suffering Sappho!” That’s a lesson Josette can learn when she’s more mature.

Professor Marston and the Wonder Women is available on Blu-ray, DVD, and digital on Jan. 30.

Read more from Yahoo Entertainment: