“We didn’t want him to become another police officer… We’ve told big, bold stories that gave [Julien Baptiste] a proper journey – he doesn’t just come in and find out some stuff and go home,” said Jack, the older of the Williams brothers by two years. “It’s about doing the right thing for the show and the characters.”

Jack Williams – plus brother Harry and the actors Tchéky Karyo and Fiona Shaw –were speaking at an RTS event previewing the new series of Baptiste, chaired by the critic and broadcaster Rhianna Dhillon.

At the end of series one, Julien Baptiste suffered a horrific personal tragedy. In the words of the man who plays him, Karyo, the ex-detective has “hit the bottom of the barrel”. Now, seeking to escape the past, Baptiste offers to help ambassador Emma Chambers (Killing Eve star Fiona Shaw), whose family have disappeared in Hungary.

Baptiste first appeared in the Williams brothers’ 2014 BBC One drama, The Missing, which starred James Nesbitt as a distraught father searching for his son in France. As you would expect from both outings of The Missing – the second, set in Germany, starred David Morrissey and Keeley Hawes as the parents of a missing girl – and the spin-off series Baptiste, series two of Baptiste is a gruelling watch.

“I wouldn’t deny that Missing one and two and Baptiste one were hard going – they weren’t a giggle fest and this isn’t a giggle fest either, but its got a little more light and shade,” said Jack Williams.

“Life is a tragic comedy,” added Karyo. “The pain is there but still we laugh.”

“It’s simply one of the best scripts I have ever read and, I know it’s sounding like a love fest, but it was a huge honour to work with Tchéky, who is one of the most passionate and brave actors,” said Shaw, adding how estimable it is to perform, like the French actor, when you are not speaking your first language.

Series two uses the brothers’ trademark twin-timeline structure, which Dhillon initially found disorientating. “That confusion is sometimes quite welcome,” replied Harry Williams. He “hates shows” that “repeat what’s going on every five minutes… trust people to stay with you.” he argued.

Filming originally began in Budapest in February 2020, but was hit by an inevitable Covid-19-enforced delay.

Hungary, said Karyo, is a “really good character”, adding that it is “another culture, [with] different attitudes and a different kind of government… Are we in Europe in Hungary? Or not?”

The locations, added Harry Williams, are not the usual “picture postcard stuff” in central Budapest. “Couldn’t afford that,” quipped Jack, who founded Two Brothers Pictures with his brother a decade ago. The siblings wrote and created The Missing and Baptiste, and their indie also produced Phoebe Waller-Bridge’s huge hit Fleabag.

Jack continued: “We couldn’t have set this anywhere else… It’s not immediately apparent in episode one why we chose Hungary, but it becomes increasingly apparent that, as the series goes on, this story had to exist there.”

Will the brothers miss writing Baptiste? “We love writing this character and this show, and once we started breaking [down] the story and realising it was going to be the last one, that was both hugely exciting and painful at the same time,” said Jack.

His brother added: “It’s [been] a huge emotional investment. It’s eight years, longer actually, since we wrote the first draft of the first Missing…  it’s [been] a joy.”

Baptiste begins on BBC One on Sunday 18 July and will be available as a box set on the iPlayer from the same day. The RTS session was produced by the RTS and Premier Communications.