Ella Purnell has been having a brilliant year — although maybe it would be more accurate to say a brilliant handful of years. From her terrific turn as mean-girl Jackie Taylor in Showtime’s survival thriller Yellowjackets to her widely-praised voice performance in Netflix’s Arcane — and who could forget her holding her own against the likes of Walton Goggins’ Ghoul in the first season of Prime Video’s Fallout? — Purnell is showing absolutely no signs of slowing down, and we’re reaping the benefits. Her latest project is the upcoming Starz show Sweetpea, adapted by Kirstie Swain from the book series of the same name; while Purnell’s character, Rhiannon Lewis, is a far cry from anything she’s ever played before, it also allows her to go the distance in her range by depicting a shy wallflower who finds a new lease on life — well, after committing a few murders, of course.

What Is ‘Sweetpea’ About?

Rhiannon Lewis (Purnell) is used to being overlooked — by her co-workers, by the cashier at the food mart (who is never happy to help), even by random strangers on the street carelessly bumping into her. It’s been that way since high school, when she became the target of vicious bullying by a group of her female peers, which was so bad that she ended up pulling most of her hair out. Years later, it’s clear that Rhiannon has never really gotten over that trauma in her adolescence, and even though her hair has grown back, her self-confidence has never truly recovered. She lives a relatively mundane life, taking care of her ailing father and working a thankless front-desk job at the local newspaper, but in her head, she’s constantly cataloging a running list of the people she’d most like to kill.

Initially, there’s no reason to think Rhiannon has real intentions of murdering anyone; who among us hasn’t had similar thoughts in our most dire moments? But then, a sequence of very unfortunate, very damaging events happens, beginning with the death of Rhiannon’s father, which plunges her world into disarray and sets her on a path to making some surprisingly shocking choices. It doesn’t help that her number-one nemesis from high school, Julia Blenkinsopp (Nicôle Lecky), is also back in her life at the exact worst time.

Rhiannon is certainly being pushed to her emotional and mental limits, but when she lashes out against an unsuspecting stranger after a night out, the resulting bloodshed transforms her in ways she never could have imagined. Now, she’s not only speaking up for herself at work, but also arguing her way into a promotion from her boss at the newspaper (Jeremy Swift). Now, she’s the one on public transportation making manspreaders uncomfortable. Rhiannon’s initial choice to murder may have been an act of spontaneity, but it also drives her to make some long-needed changes in her life. However, while she’s truly thriving for the first time, she’s also finally being noticed — and that might not be a good thing for someone who needs to stay ten steps ahead of the police detective (Leah Harvey) investigating the deadly results of Rhiannon’s actions.

Ella Purnell Is Reason Enough To Watch ‘Sweetpea’
Image Via STARZ

If that gripped you from the start, then Sweetpea is the show for you, and Purnell’s voiceover narration immediately sets the tone for the story that’s about to play out. Everyone else might be overlooking Rhiannon, but the series guarantees that we’re always privy to her inner thoughts and emotions, allowing for an understanding of how this poor woman’s inner light became so dimmed. Not only have the years of bullying taken their toll on Rhiannon’s ability to advertise her own strengths, but they’re also evident in the way she tries to avoid taking up space.

Purnell starts her performance from this diminished place, meek and soft-spoken and forever trying to avoid conflict, but that all changes once Rhiannon lashes out for the first time. After that, she fully begins to blossom, becoming more confident in herself and never apologizing for pursuing what she wants — whether that’s the aforementioned promotion to junior reporter at the newspaper, which just happens to coincide with a journalistic need to write up this sudden rash of murders in town, or hooking up with someone she’s always been too shy to ask out before. It’s no coincidence that, after surprising her new boytoy at work for a quickie, Rhiannon’s first instinct is to grab his face and implore him to look at her during the act itself. In Sweetpea, Purnell has the advantage of playing a character constantly unearthing new layers, which also allows her to display every facet of Rhiannon’s complicated personality, ranging from placidity to total, unadulterated fury.

Not every other element of the series comes together as strongly as Purnell’s performance, however. While the supporting cast is made up of some hilarious presences, some characters feel less developed. Swift is essentially playing a version of what we’ve already seen from him in Ted Lasso, albeit with the sort of oblivious misogyny that would have had Higgins sacked ages ago (he’s the one who constantly refers to Rhiannon by the patronizing diminutive that the show derives its title from). Bridgerton’s Calam Lynch, who plays Rhiannon’s cute new co-worker AJ, imbues his role with the sort of good-natured sheepishness that will have viewers rooting for the two of them to realize their mutual attraction sooner rather than later. Lecky’s Julia, as the subject of our lead’s obsessive, long-simmering hatred, is given much more to do once the two women are forced into tight quarters together, leading to moments that force Rhiannon to reconsider her coming-of-rage mission. When the season later switches perspectives halfway through to Harvey’s detective, it’s likely a move meant to illustrate that these two people on opposing sides of the law have more in common than otherwise, but Purnell is just so captivating to watch that any plot divergence has you longing to return to her scenes instead.

The outcome of Rhiannon’s pursuit of twisted justice is yet to be revealed; the cliffhanger that the story leaves off on is equally twisted and shocking, and certainly sets the stage for a bloody finale. While other shows in this vein have had difficulty sticking the landing, Sweetpea does more than enough to inspire confidence that, no matter what happens, it remains an addictive watch through to the very end.

Sweetpea premieres October 10 on Starz in the U.S.

Watch on Starz