Luke Evans plays the creator of the comic-book character Wonder Woman in this absorbing biopic.

And the heroine’s origins are quite bizarre. Evans’ William Moulton Marston is a Harvard psychologist whose academic ideas and feminist ideals fed into his creation of the Wonder Woman comic – as did the polyamorous relationship he enjoyed with his wife Elizabeth (Rebecca Hall) and their mutual lover Olive Byrne (Bella Heathcote).

We first encounter the trio in 1928 at Radcliffe, Harvard’s sister college, where Marston is expounding his theories of sexual submission and dominance to audiences of wide-eyed female students, while Elizabeth, a brilliant psychologist in her own right, chafes at the chauvinistic restrictions placed on her career.

When Marston hires student Olive as his research assistant, it’s no surprise that the atmosphere is sexually charged, but as things turn out the biggest erotic sparks are the ones struck between Olive and Elizabeth.

Writer-director Angela Robinson shows this unconventional relationship sowing the seeds for the comic-book Marston began writing in 1941. His invention of a prototype lie detector kindles the super-heroine’s fabled ‘lasso of truth’ and her costume emerges out of the trio’s penchant for role-playing and bondage.

A decidedly odd and kinky tale, but in Robinson’s hands a touchingly sweet and playful one, too.