Holmes and Watson are consulted about the arrival in England of Sir Henry Baskerville, the last of the Baskervilles, heir to the family estate on Dartmoor, following the death of Sir Henry's uncle. A local myth surrounds the Baskervilles that a vicious hound stalks the descendants of the family.
After Professor Moriarty is acquitted for murder, Holmes and Watson are visited by Ann Brandon, who tells the detectives that her brother Lloyd has received a strange note—a drawing of a man with an albatross hanging around his neck—identical to one received by her father just before his murder ten years previously.
During the Second World War, Holmes is consulted by the British Inner Council to capture a Nazi agent who broadcasts under the name the "Voice of Terror", and who appears to be running a sabotage ring in England.
A disguised Holmes helps Swiss scientist Dr Tobel to escape from Gestapo kidnappers and flee to England with his revolutionary bombsight.
A British courier is carrying top secret papers that he had put onto microfilm and inserted into a matchbook; realising he is being pursued by Nazi agents, he drops the matches into a handbag of the socialite Nancy Partridge, a fellow passenger. He is subsequently kidnapped and killed and Holmes is instructed to find his killers and the missing document.
Watson is the doctor in charge of an army hospital at Hulstone Towers in Northumberland; when his assistant, Dr. Bob Sexton, is attacked, Watson asks Holmes for help.
A series of similar suicides take place in London while Holmes is on holiday in Scotland; shortly after complaining to Watson about his health, Holmes collapses into a ravine and is missing, presumed dead.
Following the death of Lady Lillian Penrose in a small Canadian village, Holmes investigates, despite the locals blaming the murder on a glowing, murderous phantom.
On board a ship to England, a courier for the Royal Regent Museum is robbed of the Borgia Pearl by Naomi Drake.
When members of the Good Comrades club start being killed, Holmes is called to their Scottish mansion to investigate. Before a victim is killed, he receives an envelope with orange pips. After each death, the life insurance of the victim is shared between the survivors.
Holmes and Watson are consulted by Inspector Gregson of Scotland Yard to assist with the "finger murders", where young women have been murdered and one of their fingers have been removed.
Following the assassination of King Stephan of Rovinia, Holmes and Watson are engaged by that country's Prime Minister to assist with the passage of Prince Nikolas of Rovinia from his school in Britain to Algiers, where Rovianian agents can take him the rest of the way.
Holmes and Watson are hired by Ronald Carstairs and his mother Lady Margaret to protect the Star of Rhodesia diamond on a train trip from London to Scotland.
Watson is visited by Julian "Stinky" Emery, an old friend, who tells him and Holmes of a strange robbery in his house—the theft of a cheap music box from his collection.
