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.

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.

While "Sweetpea" will be a streaming exclusive, Starz also has a linear TV channel. If you don't already have Starz on cable, you can pick it up as an add-on on several live TV streaming services, including Hulu, Sling TV, Fubo, YouTube TV, Philo, and DirecTV Stream.

Fallout' star Ella Purnell discusses how she became a producer for the Sky/Starz serial killer comedy 'Sweetpea' and developing her character.

Exactly how far do you have to push a wallflower before she turns into a Venus flytrap? That’s the question at the center of Starz’s Sweetpea, the dark comedy starring Ella Purnel (Yellowjackets, Fallout) that premiered Thursday.

But Sweetpea protagonist Rhiannon Lewis, played by none other than Yellowjackets alum Ella Purnell, might be a rare exception. Maybe then, she would have had the chance to confront her teenage angst head-on,