Sinéad Keenan and Sanjeev Bhaskar in “Unforgotten”

Some of television's favorite detectives are hot on the trail of chilling cases across Europe as PBS welcomes back two crime dramas for season premieres on this side of the pond. "Unforgotten" and "Van der Valk" debut back-to-back season premieres on Sunday, Sept. 3.

London-set drama "Unforgotten" stars Sanjeev Bhaskar ("Yesterday," 2019) as DCI Sunil "Sunny" Khan and new addition Sinéad Keenan ("Showtrial") as DCI Jessica James in its fifth season of cold case deep dives. Each six-episode season centers on one decades-old case reinvigorated by newly discovered evidence. An estate reveals hints of a hidden mystery during renovations in the season premiere.

"Van der Valk" premieres the first installment of its three-episode third season following the titular cynic detective Piet Van der Valk (Marc Warren, "Flack") as he combs through the criminal underbelly of idyllic Amsterdam to solve the city's murders. A reboot of the 1972-1992 series of the same name starring Barry Foster ("Maurice," 1987), both series are inspired by the "Van der Valk" detective novels by author Nicolas Freeling. The character's stories have been adapted not just for TV but for radio and film as well.

In the season premiere of "Van der Valk," the detective chases leads in the murder of a prominent freerunner. Connections in the case to Amsterdam's drug scene send Van der Valk on a mission that puts his street smarts to the test. Maimie McCoy ("All Creatures Great and Small") stars as Insp. Lucienne Hassell, with new additions this season, Django Chan-Reeves ("Industry") as Sgt. Citra Li and Azan Ahmed ("Mood") as Sgt. Eddie Suleman. Emma Fielding ("Sanditon") returns as Van der Valk's boss, commissioner Julia Dahlman, and Darrell D'Silva ("Domina") is back this season as forensic pathologist Hendrik Davie.

The much-anticipated upcoming season of "Unforgotten" kicks off with a puzzling first case for the newest member of the cold case unit. A bit stiff and overly professional in her new role, DCI James is sent to Hammersmith, London, to investigate the discovery of remains that could possibly date back as far as the 1930s.

Uncovered during restoration work, it is not immediately clear which of the antiques in the historical home could be contemporaneous to the remains. The team must quickly figure out how to work together if they are going to construct a timeline that could very well span a century.

Returning this season are Carolina Main ("Foundation") as DC Fran Lingley, Jordan Long ("Prime Suspect: Tennison") as DS Murray Boulting, Pippa Nixon ("Angela Black") as DC Karen Willetts, Georgia Mackenzie ("Casualty") as pathologist Dr. Leanne Balcombe and Michelle Bonnard ("Blindspot") as Sally Field, Sunny's partner.

Marc Warren in “Van Der Valk”

Fair warning that spoilers lie ahead that reveal the events of the fourth season of "Unforgotten." If you are caught up on the show, then you already know who is missing from cast members returning for the new season. "Unforgotten" said goodbye last season to the beloved DCI Cassie Stuart, portrayed by "Annika" star Nicola Walker.

Stuart's tragic on-screen death imitated life in a way for Bhaskar, as he told Masterpiece in a 2021 interview, that between scenes at Stuart's bedside in hospital, "We were all sitting around talking about 'Hey, do you remember when... ?' 'Do you remember the first day you were on set?' It was that weird, weird thing of the energy mimicking the scenes that we don't see between them."

With filming of the last season interrupted by COVID-19 lockdowns, Bhaskar's performance of Stuart's eulogy was filmed and recorded in parts over many months. While he shared that it was important for him to strike the right tone when reciting the eulogy, admitting he was "terrified" that he would "get too emotional with it or that it would get swallowed inside," Bhaskar is pleased with his goodbye to his co-lead, adding, "What was nice, in the end, was that that last scene became about Sunny and Cassie ... it was cathartic to have that moment on-screen."

Losing such a central character is merely a creative challenge for "Unforgotten" series creator Chris Lang, who told Masterpiece that he and Walker worked on her exit from the show together over two seasons, asking her to stay for Season 4 so that he could, "Write [her] a proper story." Inspired by how American dramas like "Breaking Bad" deal in big swings, Lang added, "Writing out your lead — it's quite a challenge there to move forward, but it's a really good challenge."

As for what is to come in the new season, Lang looked West yet again. He told Masterpiece, "Watching [HBO's] 'Mare of Easttown,' the proportion of personal stuff to the investigative story was really high - they both elevated and contextualized each other." Lang added, "Audiences love that stuff, and I love writing it, and I've tried to find more room in this season for the personal lives of our two protagonists."

Settle in for a full night of back-to-back cozy mysteries. British import crime dramas "Unforgotten" and "Van der Valk" premiere brand-new seasons Sunday, Sept. 3, on PBS.