The 'Fallout' star takes us behind-the-scenes of playing a sidelined receptionist who develops an intoxicatingly liberating taste for murder in the Starz dark comedy.

In the new Starz and Sky Atlantic comedic thriller Sweetpea, based on the book series of the same name by C.J. Skuse, a sheepish woman who is ignored and dismissed unleashes her inner wolf. And this girl got fangs.

Adapted from the novel by C.J. Skuse, the drama stars the 'Yellowjackets' alum as a bullied and overlooked young woman who reaches a violent breaking point.

Sweetpea' star and executive producer Ella Purnell explained why depictions of female rage trend is an 'untapped' genre.

On a flight not so long ago, Ella Purnell managed to terrify the woman sat next to her after accidentally giving her a glimpse of the recent viewing history on her laptop. “It was basically 50 shows about serial killers,

Purnell, as expected, saves Sweetpea from the brink of shlock. You can almost hear Rhiannon’s brain ticking as she quickly works out her next move and the moments in which she loses control (ie, drives her pocketknife into the neck of an unsuspecting bloke resulting in blood spurting all over the shop) are genuinely thrilling.

Sweetpea is the coming of age meets female rage we didn’t know we needed, and Ella Purnell’s portrayal of quiet wallflower-turned-serial killer Rhiannon is dark, twisted and deeply relatable.

You don’t have to have seen the many trailers to guess that the Sweetpea in the title of Sky Atlantic’s new thriller Sweetpea isn’t all that sweet. In the opening scene of episode one, Rhiannon (Ella Purnell) reels off a list of all the people she’d like to kill.