Nabhaan Rizwan, a South Asian actor, plays Ronny Devereux, originally an English house party guest, and Nyasha Hatendi portrays Dr. Cyril Matip, a Black Cameroonian inventor replacing the book's German Herr Eberhard, with plot elements alluding to German colonial atrocities like the Douala massacre, adding a layer of historical critique on imperialism. These changes expand diversity in a traditionally all-white upper-class ensemble, extending to other roles amid a cozy mystery framework.

The storyline modernizes with flashbacks and motivations like Lady Caterham's grief over her WWI-dead son driving the conspiracy, blending contemporary emotional depth into the whodunit. Creator Chris Chibnall, known for inclusive works like Doctor Who, emphasizes character studies over pure plot, but avoids overt lectures or LGBTQ+ focal points.

Audience reception includes minor backlash on platforms like Reddit decrying 'woke mind virus' for the anachronistic Black Cameroonian inventor and forced diversity, though overall reviews praise performances and engagement without widespread 'go woke go broke' fallout. Progressive elements shape casting and subtly influence themes but do not dominate the entertainment-focused narrative.