D'Artagnan is forced to join forces with Milady to save Constance, who was kidnapped before his eyes. But as war is declared and Athos, Porthos and Aramis have already joined the front, a secret from the past shatters old alliances.

Four detectives. Four timelines. One body. To save Britain's future, they'll need to solve the murder that altered the course of history first.

D'Artagnan arrives in Paris trying to find his attackers after being left for dead, which leads him to a real war where the future of France is at stake. He aligns himself with Athos, Porthos and Aramis, three musketeers of the King.

In the West End of 1950s London, plans for a movie version of a smash-hit play come to an abrupt halt after a pivotal member of the crew is murdered. When world-weary Inspector Stoppard and eager rookie Constable Stalker take on the case, the two find themselves thrown into a puzzling whodunit within the glamorously sordid theater underground, investigating the mysterious homicide at their own peril.

After finding a trove of love letters from 1965, a reporter sets out to solve the mystery of a secret affair — while embarking on a romance of her own.