Belgian detective Hercule Poirot and spinster sleuth Miss Marple weren't Dame Agatha Christie's only creations. She also invented Tommy and Tuppence Beresford, an ordinary married couple who stumble into spy craft and end up being rather good at it. In these new adaptations of two classic mysteries, set in 1950s Britain at the start of the Cold War, Tommy and Tuppence return to the small screen, bickering, sweet on each other, and soon knee-deep in danger.