Mable Havelock and Violet Ficher are on a scenic bus tour of the Nordic capital cities of Europe and Russia. The tour culminates in Moscow. Where The tour director is murdered. There is a busload of suspects to choose from. A flirtatious woman and her jealous husband. A professor of Nordic History who is ill-informed. Two world travellers who describe themselves as gypsies and a mysterious man who is hiding something. The tour director's assistant and bus driver; both have an axe to grind against the tour director Hilda Karlson.
Add to the mix smugglers and thieves. And a case of mistaken identity. But unfortunately, the prime suspect is Mabel. Mabel and Violet will have to use all their skills and ingenuity to solve the murder in Moscow. And prove to the Russian police Mabel's innocence.