Hoping to make a clean break from a fractured marriage, Agatha Christie boards the Orient Express in disguise. But unlike her famous detective Hercule Poirot, she can't neatly unravel the mysteries she encounters on this fateful journey. Her cabinmate Katharine Keeling's first marriage ended in tragedy, propelling her toward a second relationship mired in deceit. Nancy Nelson - newly married but carrying another man's child - is desperate to conceal the pregnancy and teeters on the brink of utter despair.
In the midst of the Second World War, Eva receives the devastating news that her husband is missing and presumed dead. Neither wife nor widow, she lives in a numb state of limbo until, in the heat of an English summer, she meets Bill, a black American GI. Despite their vastly different backgrounds, neither can deny the love that overcomes them in the frantic weeks that follow, when every day could be their last.
The world of Cardiff's sex trade hits the headlines when a woman is butchered and left for dead. Pauline distributes condoms to the women of the red light district and is known locally as "the rubber woman". She and Megan, a forensic psychologist, make it their mission to stop more women from becoming victims. They don't know it yet, but one of them is already marked out for death.