When ITV’s The Bletchley Circle premiered in the UK in 2012, it was a clever spin on a British specialty: the period whodunit.

Instead of Sherlock or Father Brown or Detective Foyle outsmarting murderers and villains, we had four female cryptographers who used to work at Bletchley Park. Feeling bored and boxed in by their post-Second World War lives, the women dusted off their code-breaking skills to outwit a London serial killer. Along the way, they also had to outplay many of the men around them—including homicide detectives and their own husbands—who were prevented by secrecy laws from knowing what they did during the war and wanted them to simply go back to who and what they were before the bombs started falling.

Many of those qualities are still present in the new eight-episode, four-mystery spinoff series, The Bletchley Circle: San Francisco, which premieres on Friday, Sept. 14, at 8 p.m. ET on Citytv. However, a change of location and some intriguing new characters shake it up enough to make it feel fresh and worthwhile. Set in 1956, three years after the original series ended, sleuthing codebreakers Millie (Rachael Stirling) and Jean (Julie Graham) set off for the Bay Area to investigate a death that has shocking similarities to the murder of a young Bletchley Park colleague in 1942. Once there, they meet up with former American servicemembers Iris (Crystal Balint) and Hailey (Chanelle Peloso) and convince them to help track down who’s responsible for the killings.

Like the women in the original series, Iris and Hailey have struggled to find satisfaction in the post-war era. Jazz pianist and former codebreaker Iris now works in obscurity as a research assistant at Berkeley, while former weapons designer Hailey is desperate to find a new outlet for her mechanical genius. In learning about their lives, viewers also get a look at some of the social issues percolating in 1950s San Francisco. For instance, the first episode, “Presidio”— written by former Bitten executive producer Daegan Fryklind—gives viewers a taste of the historic Fillmore District, an area known both for its bustling jazz scene and for being targeted by various gentrification efforts. In an early scene, Iris’ son sets off to protest a plan to drive African Americans from the neighbourhood, and later, Iris’ former Presidio colleague laments that her Japenese American family was also driven out of the area.

Iris, in particular, breathes new life into the codebreaker conceit of the show, giving viewers a peek into the little-known history of black women in the Signal Intelligence Service. On that front, Calgary-native Balint gives a strong performance as a woman who has much to lose by going along with a couple of Brits who show up in her jazz club one night. Meanwhile, Vancouver-born Peloso is irresistibly plucky as eager go-getter Hailey. And what more can you say about Stirling and Graham? They were great in the first series and they’re great here. Graham is particularly good in a London-set scene where she learns her age and gender mitigate her smarts in the eyes of a young Foreign Service Office agent.

Speaking of London—and of San Francisco, for that matter—this series wasn’t produced in either location. It was filmed in Vancouver. However, there are enough shots of trolleys and Victorian houses to give it a convincing Northern California feel. There’s also a splash more colour and light in the production design when compared to its UK predecessor, highlighting both the change in climate and the contrasting post-war conditions of bomb-riddled London and unscathed San Fransisco.

As for the wisdom of transplanting a British show into an American setting and then shooting it in Canada, showrunner and executive producer Michael MacLennan points out that Canadians are “uniquely qualified” to act as translators of British and American sensibilities. And based on the screeners, he appears to be right. Produced by Omnifilm Entertainment in association with BritBox and World Productions, who made the original, the series retains its British pedigree while shining a light on some infrequently explored—and still painfully relevant—American stories. And it offers up some solid mysteries and compelling female camaraderie along the way.

The Bletchley Circle: San Francisco airs Fridays at 8 p.m. ET on Citytv.

Images courtesy of Omnifilm