London, 1921: Mabel Canning is proud to be a modern woman working for the Useful Women’s Agency, carrying out tasks for gentlewomen from flower arranging to washing muddy dogs. But when she answers the door for wealthy widow Rosalind Despard, she almost chokes on her cucumber sandwich when she finds a soldier’s body on the doorstep. As she offers tea to the policemen of Scotland Yard, Mabel can’t resist getting drawn into the investigation.

Hayley Burke has landed a dream job. She is the new curator of Lady Georgiana Fowling's First Edition library. The library is kept at Middlebank House, a lovely Georgian home in Bath, England. Hayley lives on the premises and works with the finicky Glynis Woolgar, Lady Fowling's former secretary. Mrs. Woolgar does not like Hayley's ideas to modernize The First Edition Society and bring in fresh blood. And she is not even aware of the fact that Hayley does not know the first thing about the Golden Age of Mysteries.

Pru Parke always dreamed of living in England. And after the Dallas native follows an impulse and moves to London, she can't imagine ever leaving - though she has yet to find a plum position as a head gardener. Now, as the sublet on her flat nears its end, the threat of forced departure looms.

London, 1941: Miss Jane Treen is at her desk, strong black coffee in hand and fluffy ginger cat by her side, when her top-secret government work is interrupted by an urgent call to Devon. A woman has been found dead in a lake in a place where she shouldn’t have been. Jane needs to gather the clues and find the killer before someone else from the agency gets hurt… Shy and handsome code-breaker Arthur Cilento is bewildered by the arrival of the efficient Miss Treen and her cat Marmaduke.

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…

With only days left until Christmas, uncle Albert is in a tizzy. The annual Twelve-Birds-Of-Christmas Dinner is looming, and his scheme to procure a copy of the latest book craze to sweep the Royal Society for Natural History Appreciation has been thwarted. Now, in a desperate bid to secure a Christmas miracle, Lady Caroline and Uncle Albert travel to an isolated castle on the Yorkshire moors in pursuit of the only available copy of the coveted book.

England. 1923. After a year away at finishing school where she learned etiquette, deportment, and the difference between a fish fork and a salad one, Kitty Worthington is eager to return home. But minutes after she and her brother Ned board the Golden Arrow, the unthinkable happens. A woman with a mysterious connection to her brother is poisoned, and the murderer can only be someone aboard the train. When Scotland Yard hones on Ned as the main suspect, Kitty sets out to investigate.

London, 1861. Samantha Kingston has lived under the control of her overbearing uncle since the death of her parents six years ago. Trapped by the conventions of her gender and social class, she is desperate to find a way out. But when her aunt and uncle are murdered, the freedom she sought seems even further out of reach. A suspect in the crime, she finds herself on the run, unsure whom to trust, lost in the underworld she had only ever read about in the pages of a Dickens novel.

It's 1911, and war is brewing across Europe. However, Melody Chesterton, an independent young woman with her own fortune, has more important things on her mind. Melody is determined to do more with her life than marry well; she wants exciting escapades with perhaps some romance sprinkled in along the way. Chaperoned by her older brother, Rat, who secretly works for Britain's newly formed Secret Service Bureau, Melody sets off for the first stop on her Grand Tour of Europe, Venice.

It’s 1924. Lady Ellen of Ashcombe Hall is on a relaxing hotel break to recuperate. Her nemesis is found dead in the restaurant, face down in his pea and ham soup. Can she confront her past to solve the mystery? Lady Ellen seeks respite in the charming seaside town of Branden Bay, whilst her home, which was used as a convalescent home for war veterans, is being refurbished to its former glory.

Cressida Fawcett is heading to the English countryside for a weekend of cocktails and partying at her friend’s glamorous mansion, the location of a recent diamond heist. But just hours after her arrival, Cressida is woken by an almighty scream. Rushing to the landing, she looks down into the great hall to find a trembling maid standing next to the body of Harry, the friendly young chandelier cleaner. Everyone believes Harry’s death was an accident. But as Cressida examines the opulent hall and the beautiful grounds, she thinks something darker is afoot.

June 1933. Independent, young Kitty Underhay has been left in charge of her family’s hotel, The Dolphin, on the tranquil English coast. But when several rooms are broken into and searched, including Kitty’s own, she quickly realizes that something out of the ordinary is afoot at the hotel. Soon, rumors are flying in the cozy town that someone is on the hunt for a stolen ruby. A ruby that Kitty’s mother may well have possessed when she herself went missing during the Great War.

Spring, 1905: Free-spirited like the Thoroughbreds she rides across the Kentucky countryside, Stella takes adventure by the reins when she's asked to attend a mysterious wedding in rural England. But once she arrives at the lush Morrington Hall estate, her cold and ambitious father confesses that he won't only give away his best racehorses as gifts - he has also arranged to give away his daughter as bride to the Earl of Atherly's financially strapped son. Stella refuses to be sold off like a prized pony. Yet despite a rough start, there's something intriguing about her groom-to-be.

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.

Disgraced society “it” girl, Lady Caroline, has been shipped off to the French Riviera to spend remedial time with gout-impaired Uncle Albert. Her crime? An ill-advised scavenger hunt through London, with social-status-ruinous consequences.