Pursuit to Algiers (1945)

About to leave London for a much-needed vacation, Holmes and Watson receive a cryptic invitation. Intrigued, Holmes accepts and is met by the prime minister of the fictional country of Rovinia, who begs him to escort Prince Nikolas home. It turns out that his father has been assassinated, and Nikolas is the heir. Holmes agrees.

Arrangements have already been made for an airplane. When it develops problems, a smaller replacement only has room for the prince and Holmes, leaving Watson behind. When Watson protests, Holmes suggests he follow on a passenger ship bound for Algiers.

On the voyage, Watson reads that the airplane has crashed in the Pyrenees and that it is unlikely that there are any survivors. Fortunately, Holmes has an aversion of plans made by others and is aboard the ship with Nikolas. He instructs Watson to introduce the prince to the other passengers as his nephew. Though Watson suspects everyone, from American singer Sheila Woodbury to exercise fanatic Agatha Dunham to a secretive pair who later turn out to be archeologists, of being killers, it is not until the ship makes an unscheduled stop at Lisbon that the real Russian agents come aboard: Gregor, circus knife thrower Mirko, and a hulking mute named Gubec.

First, Mirko tries to kill Holmes with a throw through a porthole, then Gregor substitutes an explosive party favor, but Holmes foils both attempts. Finally, the villains succeed in kidnapping the prince when they dock at Algiers, only for Holmes to reveal that the "prince" was a decoy; the real prince had been posing as a steward, hidden in plain sight the whole time.