Mia McKenna-Bruce Lady Eileen `Bundle' Brent Actor Helena Bonham Carter Lady Caterham Actor Martin Freeman Superintendent Battle Actor Alex Macqueen George Lomax Actor Guy Siner Tredwell Actor Chris Chibnall Writer Chris Sweeney Director, Executive Producer Suzanne Mackie Executive Producer Agatha Christie Writer Chris Sussman Executive Producer James Prichard Executive Producer Andy Stebbing Executive Producer