Fallout Star Ella Purnell's Deadly Series On Prime Video Is Perfect For Dexter Fans

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"Dexter" has returned (again), because Michael C. Hall's killer of serial killers is back in the new series "Dexter: Resurrection" (with other familiar faces in tow). If you think Dexter Morgan has run his course at this point, then fear not! There are plenty of other serial killer shows out there, from "You" to the acclaimed horror anime "Monster" to the British series "Sweetpea," starring (and executive produced by) Ella Purnell as unassuming murderer Rhiannon Lewis.

A U.K. production that aired on Sky Atlantic, "Sweetpea" adapts a book series by CJ Skuse. The show was distributed in the U.S. by Starz — the first three of the series' six episodes are now streaming for free on Prime Video.

Rhiannon is a wallflower, living in her childhood home with her dad Tommy (David Bark-Jones) and working as a secretary ("administrative assistant," she insists) at the local newspaper. She's been ignored at best, bullied at worst throughout her life. Her nickname that gives "Sweetpea" its title comes from her boss Norman (Jeremy Swift). He thinks so little of her that he uses her desk (and sometimes Rhiannon herself) as a coat rack. But as the "Sweetpea" poster warns, "It's always the quiet ones."

As Rhiannon goes about her day, she maintains an inner monologue: "People I'd Love to Kill." People on the list range from manspreaders on the bus to her annoying coworkers to especially her childhood bully Julia (Nicôle Lecky). "Sweetpea," in turn, follows Rhiannon as she finally starts crossing names off her to-do list.

Now, to be fair, Rhiannon has a really bad day before she begins stabbing anyone. Norman turns her down for a promotion, claiming she doesn't have the "roar" to be a journalist. It gets worse: Rhiannon's dad dies, her sister Seren (Alexandra Dowling) wants to sell his house and has commissioned Julia (now an estate agent) to do it, Rhiannon's dog gets hit by a car, and, finally, a drunk guy literally (accidentally) pisses on her. After the last one, she stabs the drunk man to death... and finally feels power like she never has.

"Sweetpea" earns some "Dexter" comparisons, but really it's more of a feminine "Falling Down" or "Batman: The Killing Joke," i.e. stories about how bad days can drive seemingly normal people to do horrible things. In one episode, Rhiannon sings karaoke to Katy Perry's "Roar," the ultimate fluffy girl power pop anthem. But lionesses don't just roar, they bite and devour with teeth sharp as Rhiannon's knife.

Rhiannon is an irresistibly sympathetic protagonist; you will feel sorry for her even with the mistakes (to put it mildly) she makes. The biggest way "Sweetpea" compares to "Dexter" is how it can make you root for a serial killer to succeed, even though you really shouldn't. Rhiannon at least has enough of a conscience to feel guilty, but she's done letting others treat her with ignorance and contempt. Her character is a warning about the danger of keeping your anger bottled up. If you hold rage in your head and heart without asserting yourself, then the smallest inconveniences will make you feel like a victim, primed to eventually explode.

Purnell plays Rhiannon as someone so shy they've got no clue what confidence feels like. She also looks innocent, especially with those big anime girl eyes, providing the needed contrast in how Rhiannon appears and how she acts. It's not all looks, to be clear.

Meanwhile, "Sweetpea" is miles apart from Purnell's previous live-action projects. Watch her interviews, too, and you can tell she's extroverted and charismatic. Those are qualities that her other roles, like the plucky Lucy in "Fallout" or preppy queen bee Jackie in "Yellowjackets," have banked on. She suppresses that just enough to make Rhiannon an introvert but still weaponizes it to make the audience like her. For the Fellowjackets: Rhiannon is like if Purnell had played Shauna (Sophie Nélisse) instead of Jackie, and boy, it still works!

Speaking to The Hollywood Reporter, Purnell discussed her way into Rhiannon's character:

"I can never justify murder, and I can never understand how you can take someone's life. I can't. But what I can get on board with — and what I can relate to — is the feeling of being seen and having impact. And, what could be more permanent and impactful than ending someone's life?

Long story short: "Sweetpea" is a good series, but Purnell's performance in it is great. Thankfully, the show has been renewed for a second season after its first season ended on a hell of a cliffhanger — and while the series has already changed elements of the original books' story, there's more of them to adapt. I'm not sure where Rhiannon's journey will go from here, but I'm excited to follow it.

"Sweetpea" season 2 does not have a release date at this time.