June, 1916. With a world war raging on the continent, exhausted John H. Watson, M.D. is operating on the wounded full-time when his labors are interrupted by a knock on his door, revealing Sherlock Holmes, with a black eye, a missing tooth and a cracked rib. The story he has to tell will set in motion a series of world-changing events in the most consequential case of the detective’s career. Amid rebellion in Ireland and revolution in Russia, Germany has a secret plan to win the war, and Sir William Melville of the British Secret Service dispatches the two aging friends to learn what the scheme is before it can be put into effect. In pursuit of a mysterious coded telegram sent from Berlin to an unknown recipient in Mexico, Holmes and Watson seek to foil the schemes of Holmes’ nemesis, the escaped German spymaster Von Bork.

In 1910, Dr. John Watson travels to Egypt with his wife, Juliet. Her tuberculosis has returned, and her doctor recommends a stay at a sanitarium in a dry climate. But while his wife undergoes treatment, Dr. Watson bumps into an old friend --- Sherlock Holmes. An English Duke with a penchant for Egyptology has disappeared, leading to enquiries from his wife and the Home Office. Holmes has discovered that the missing duke has indeed vanished from his lavish rooms in Cairo and that he was on the trail of a previous undiscovered and unopened tomb. With the help of Howard Carter, Holmes and Watson are on the trail of something much bigger, more important and more sinister than an errant lord.

January 1905: Sherlock Holmes and Dr. John H. Watson are summoned by Holmes' brother, Mycroft, to undertake a clandestine investigation. An agent of the British Secret Service has been found floating in the Thames, carrying a manuscript smuggled into England at the cost of her life. The pages purport to be the minutes of a meeting of a secret group intent on nothing less than taking over the world. Based on real events, the adventure takes the famed duo --- in the company of a bewitching woman --- aboard the Orient Express from Paris into the heart of Tsarist Russia, where Holmes and Watson attempt to trace the origins of this explosive document. On their heels are desperate men of unknown allegiance, determined to prevent them from achieving their task.