London, 1851. With the opening of the Great Exhibition at hand, interest in mounting in the engineering triumphs of the railways, but not everyone feels like celebrating. In an audacious attack, the London to Birmingham mail train is robbed and derailed, causing many casualties. Planned with military precision, this crime proves a challenge to Detective Inspector Robert Colbeck who fights to untangle a web of murder, blackmail and destruction.

May 1915. As zeppelin bombs fall on London and with the sinking of the Lusitania, anti-German hysteria reaches fever pitch and attacks on German immigrants surge. Not even the West End of London is immune. Jacob Stein's bespoke tailoring business comes under brutal attack, leaving his safe ransacked, his daughter, Ruth, raped and Jacob dead.

December 1899. After the death of her beloved grandmother, Cleopatra Fox moves into the luxury hotel owned by her estranged uncle in the hopes of putting hardship and loneliness behind her. But the poisoning of a guest on Christmas eve throws her new life, and the hotel, into chaos. Cleo quickly realizes no one can be trusted, not Scotland Yard and especially not the hotel’s charming assistant manager.

After rising to prominence for his role investigating the case of Jack the Ripper, former Detective Inspector Daniel Wilson is now retired. Known for his intelligence, investigative skills, and most of all his discretion, he's often consulted when a case must be solved quickly and quietly. So when a body is found in the Egyptian collection of the Fitzwilliam Museum in Cambridge, Wilson is called in.  

Chasing his dream of a glittering architectural career, Merlin Richards has left the Welsh valleys for the Arizona desert, propelled by a handwritten note from the legendary Frank Lloyd Wright. Richards arrives at the Arizona Biltmore hotel, where he meets a beautiful young designer named Rosa Lustig. Like every man in her circle, Merlin is captivated by Rosa but soon finds himself the prime suspect in her murder.

March, 1918. British newspapers carry the dreadful news that the German Spring Offensive has begun, with thousands of British lives lost. Detective Sargeant Joe Keedy is awaiting release from hospital in London and is anxious to resume the fight against crime on the Home Front. Late one night, a bank is raided by a gang and the villains escape by car with a sizeable haul. Detective Inspector Harvey Marmion is put in charge of the case, but without Keedy at his side he faces an uphill battle to solve this perplexing case.

On the shocking discovery of a passenger's body on the Great Western Railway excursion train, Detective Inspector Robert Colbeck and his assistant, Sergeant Victor Leeming, are dispatched to the scene. Faced with what initially appears to be a motiveless murder, Colbeck is intrigued by the murder weapon - a noose. When it emerges that the victim had worked as a public executioner, Colbeck realises that this must be intrinsically linked to the killer's choice of weapon.

September, 1940. The sun is shining, and in the midst of the good weather Londoners could be mistaken for forgetting their country was at war - until the familiar wail of the air-raid sirens heralds an enemy attack. The Blitz has started, and normal life has abruptly ended - but crime has not. That night a man's body is discovered in an unmarked van in the back streets of West Ham. When Detective Inspector John Jago is called to the scene, he recognises the victim: local justice of the peace Charles Villiers. The death looks suspicious, but then a German bomb obliterates all evidence.

At the end of her first unsuccessful season out in society, Lady Georgiana has all but given up on attracting a suitable man - until she receives an invitation to a masked Halloween ball at Broxley Manor. Georgie is uncertain why she was invited, until she learns that the royal family intends to marry her off to a foreign prince, one reputed to be mad.

Singapore, 1910 - Desperate for a fresh start, Harriet Gordon finds herself living with her brother, a reverend and headmaster of a school for boys, in Singapore at the height of colonial rule. Hoping to gain some financial independence, she advertises her services as a personal secretary. It is unfortunate that she should discover her first client, Sir Oswald Newbold - explorer, mine magnate, and president of the exclusive Explorers and Geographers Club - dead with a knife in his throat.

After a routine delivery, midwife Sarah Brandt visits her patient in a rooming house and finds that another boarder, a young girl, has been killed. At the request of sergeant Frank Malloy, she searches the girl's room and discovers that the victim is from one of the most prominent families in New York - and the sister of an old friend. The powerful family, fearful of scandal, refuses to permit an investigation. But with Malloy's help, Sarah begins a dangerous quest to bring the killer to justice before death claims another victim.

Olivia Denis is a content young wife with a carefree life in late 1930s London. Then her world is shattered with the violent death of her husband, Reggie. The police want to call it a suicide and close the case, but Olivia knows Reggie couldn't possibly have fired the fatal shot. Further mysteries surface surrounding her husband's death. Did the trustworthy Foreign Office employee betray government secrets? Was his murder linked to the death of a German embassy clerk the same night? And who searched their flat?

December 1940. With the Luftwaffe pounding the city nightly, Londoners seek refuge in underground stations. Aldwych has been taken out of service to provide shelter for the British Museum's priceless Elgin Marbles, as well as civilians escaping the bombing. When the body of a young man is discovered on the tracks, wearing evening dress but barefoot, Detective Chief Inspector Coburg and Sergeant Lampson are on the case. Before long, more bodies are discovered, and Coburg's wife Rosa becomes a target for the brutal killer.

September 1907. George Dillman sets sail from Liverpool to New York on the Lusitania's maiden voyage. Posing as a passenger, Dillman is in fact an undercover detective hired by the Cunard Line to keep an eye out for petty crimes. But after some uneventful days aboard, the ship’s blueprints are stolen and then a body is found. As Dillman works to get to the bottom of the crimes, he makes an unusual friend, first-class passenger Genevieve Masefield, and the two uncover secrets aboard the ship that prove explosive.

In the sleepy village of Cookingdean, Dr Nell Ward is busy working in the grounds of a local manor house. Whilst inspecting an old tunnel, she did not expect to overhear a murder. As the only person with any clues as to what happened, Nell soon finds herself in the middle of the investigation. Desperate to clear her name Nell, along with her colleague Adam, set out solving the murder using their skills as ecologists to uncover details no one else would notice. But it soon becomes clear that playing Agatha Christie is much harder than it might, at first appear.