In a London slowly recovering from the ravages of World War II, two very different women join forces to launch a business venture in the heart of Mayfair - The Right Sort Marriage Bureau. Miss Iris Sparks, avuncular and unmarried, and Mrs. Gwendolyn Bainbridge, practical and widowed with a young son, are determined to achieve some independence and do some good in a rapidly changing world. But the promising start to their marriage bureau is threatened when their newest client is found murdered and the man arrested for the crime is the prospective husband they matched her with.

It’s 1924, and Blix Windway has made a career out of her wanderlust, giving lectures to ladies’ groups about everything from the flora of the American desert to the beauty of the Swiss Alps, but she needs new material for her talks. She strikes what seems to be an ideal agreement with an eccentric older lady. Blix will be her travel companion during a journey to Egypt, helping to smooth the way through customs and coordinate sightseeing tours.

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.

Egypt, 1926. Fiercely independent American Jane Wunderly has made up her mind: she won't be swept off her feet on a trip abroad. Despite her Aunt Millie's best efforts at meddling with her love life, the young widow would rather gaze at the Great Pyramids of Giza than into the eyes of a dashing stranger. Yet Jane's plans to remain cool and indifferent become ancient history in the company of Mr. Redvers, a roguish banker she can't quite figure out.

It's the 1930s, and a mysterious illness is spreading over Scotland. But the noble and ancient family of Inverkillen, residents of Loch Down Abbey, are much more concerned with dwindling toilet roll supplies and who will look after the children now that Nanny has regretfully (and most inconveniently) departed this life. Then Lord Inverkillen, earl and head of the family, is found dead in mysterious circumstances. The inspector declares it an accident but Mrs MacBain, the head housekeeper, isn't so convinced.