actors Matthew Beard and Juergen Maurer are thrilled to be decked out in period costume and reprising their respective roles as self-confident psychoanalyst Max Liebermann and gruff Inspector Oskar Rheinhardt when What to Watch joins them for a virtual interview from the set of their popular 1900s-set procedural drama. “I always have this slightly nervous flutter before we start filming where I wonder, ‘How do I get back into this?’” smiles London-born Matthew, 35. “But then I put on Max’s stiff collar, get strapped into his waistcoat and braces, and we snap into it pretty much straight away, don’t we?” “Yes, I just love it when we put on our costumes, stand next to each other and click-clack, there we are,” agrees Austrian star Juergen, 57.

“The relationship between Oskar and Max has evolved over time, and so has our relationship as actors. I hope I’m not exaggerating when I say we like each other very much and are good friends!” Inspired by the best-selling Max Liebermann Mystery novel franchise by Frank Tallis, the fourth season begins on BBC2 on Sunday, August 4 and will see a format change with a single story playing out across two feature-length episodes, rather than three standalone cases. When we catch up with Max and Oskar it’s 1909, they haven’t seen each other for a while, but it doesn’t take them long to pick up where they left off.

.. which is just as well because complete trust in each other is paramount, as they face their most da.