In February 1915, the Great War is still raging on the Western Front, but in Westminster, at the centre of Hardcastle's bailiwick, a policeman is shot dead. At first, Hardcastle believes the murderer to have been a disturbed burglar. But as enquiries continue, attention focuses on an antiquarian bookseller, a struggling artist, a reporter, officers of the Royal Flying Corps, both in England and in France, and the activities of Isabel Plowman, the wife of one of them and the lover of others.

England, 1925. After years shut away from the world, former detective Lord Edgington of Cranley Hall plans a grand ball to celebrate his seventy-fifth birthday. But when someone starts bumping off members of his scheming family, the old man enlists his teenage grandson to help find the killer, before one of them is next.

December 1927. Mystery-writer Marius Quin has one previous bestseller, endless looming mortgage payments, and no idea how to write his next book. When his childhood friend Lady Isabella Montague invites him to an intimate New Year’s Eve party hosted by a narcissistic actor, Marius seizes upon the distraction. With his perpetually glum Basset hound along for the ride, he navigates the snowy lanes to the opulent estate of Everham Hall. As the celebrations begin, fireworks light up the sky, champagne corks pop, and then the host is murdered…

Lady Emily Hardcastle is an eccentric widow with a secret past. Florence Armstrong, her maid and confidante, is an expert in martial arts. The year is 1908 and they've just moved from London to the country, hoping for a quiet life. But it is not long before Lady Hardcastle is forced out of her self-imposed retirement. There's a dead body in the woods, and the police are on the wrong scent. Lady Hardcastle makes some enquiries of her own, and it seems she knows a surprising amount about crime investigation...

The village of Badger's Drift is the essence of tranquillity. But when resident and well-loved spinster Miss Simpson takes a stroll in the nearby woods, she stumbles across something she was never meant to see, and there's only one way to keep her quiet. Miss Simpson's death is not suspicious, say the villagers. But Miss Lucy Bellringer refuses to rest: her friend has been murdered. She is sure of it.

Edinburgh, 1911: When Maud McIntyre and her lady’s maid, Daisy, form a detective agency, they never dream their first case will take place at a glamorous house in the Scottish Highlands. But when the duchess of Duddingston, concerned that a notorious jewelry thief will target her lavish weekend party, employs Maud to go undercover as a guest to find the culprit, the agency has its first case to solve....

August, 1940. On the streets of London, locals watch with growing concern as German fighter planes plague the city’s skyline. But inside the famous Ritz Hotel, the cream of society continues to enjoy all the glamour and comfort that money can buy during wartime - until an anonymous man is discovered with his throat slashed open. Detective Chief Inspector Coburg is called in to investigate, ably assisted by his trusty colleague, Sergeant Lampson.

Spring, 1918. The Great War is at a crucial stage, the Germans are making one last push into France, and the Allies are struggling to hold them back. Battle lines are shifting, and men, and their machines, are being sent up and down the front to shore up defenses. Major Heathcliff Lennox, and his batman Greggs, are told to report to their new HQ. They set off on a sunlit day to fly the distance, but the enemy is never far away, and disaster strikes. They're sent crashing to the ground behind enemy lines, where life, death, and love await.

Horniman, Birley and Craine is a highly respected legal firm with clients reaching to the highest in the land. When a deed box in the office is opened to reveal a corpse, the threat of scandal promises to wreak havoc on the firm's reputation - especially as the murder looks like an inside job. The partners and staff of the firm keep a watchful and suspicious eye on their colleagues, as Inspector Hazlerigg sets out to solve the mystery of who Mr Smallbone was - and why he had to die.

The year is 1920: Flying in the face of convention, legendary American adventuress Beryl Helliwell never fails to surprise and shock. The last thing her adoring public would expect is that she craves some peace and quiet. The humdrum hamlet of Walmsley Parva in the English countryside seems just the ticket. And, honestly, until America comes to its senses and repeals Prohibition, Beryl has no intention of returning stateside and subjecting herself to bathtub gin.

Chief Inspector Macdonald has been invited to a treasure hunt party at the house of the Graham Coombe, the celebrated publisher of Murder by Mesmerism. The clues of the hunt have been devised by Coombe's thriller-writer friends, disguised on the night under literary pseudonyms. The fun comes to an abrupt end, however, when 'Samuel Pepys' is found murdered in the telephone room in bizarre circumstances.

Evelyn Christie has resigned herself to another long, boring weekend at Hessleham Hall, the home of her husband, Tommy's, family. However, it turns out to be anything but dull when his uncle, the Earl of Northmoor, is shockingly murdered! Evelyn must use all of her sleuthing knowledge, gained whilst she was a member of the Police force during the war, to find out who the murderer is before the bungling local police force decide the Earl was bumped off so Tommy could inherit his title.

Detective Sergeant Chris Waters got the call at 05.29 that July morning. This is it, said DCI Reeve, you'll be first there, it's all yours, you're the crime scene manager. Suddenly, after months of waiting and wondering, Waters finds himself in at the deep end, and alone at the scene of a puzzling murder. As the investigation proceeds, the detectives at Kings Lake Central find themselves visiting familiar places and talking to some familiar faces, while old enmities reappear in the incident room. Before this is over, Chris Waters will need to make a career-changing decision.

London, 1925. With their band the Dizzy Heights, jazz musicians Ivor ‘Skins’ Maloney and Bartholomew ‘Barty’ Dunn are used to improvising as they play the Charleston for flappers and toffs, but things are about to take a surprising turn.

1940, England: Evelyne Redfern, known as “The Parisian Orphan” as a child, is working on the line at a munitions factory in wartime London. When Mr. Fletcher, one of her father’s old friends, spots Evelyne on a night out, Evelyne finds herself plunged into the world of Prime Minister Winston Churchill’s cabinet war rooms. However, shortly after she settles into her new role as a secretary, one of the girls at work is murdered, and Evelyne must use all of her amateur sleuthing expertise to find the killer.