Sir Charles Baskerville is found dead on Dartmoor, with his face contorted in terror and the footprints of a huge dog near his body. On arrival in England, Sir Charles's American heir, now Sir Henry Baskerville, engages Holmes to come to Devon and get to the bottom of the age-old legend of the Hound of the Baskervilles - a phantom which kills.From the outset, Holmes is convinced there is a human murderer at work and he lays a deep plan to foil him.

Holmes is asked by the country's Prime Minister to aid in the recovery of a stolen diplomatic letter, which, if published, might lead England into war.

The body of one Cadogan West is found in an underground tunnel near Aldgate Station, with his skull smashed, and Holmes is puzzled by the interest his brother Mycroft is showing in the case. Mycroft explains that the top secret plans for a new submarine were in the dead man's pocket, but three of the ten pages were missing when the body was found. Mycroft, on behalf of the British Government, asks his brother to find the missing pages.

A man dies suddenly of a mysterious fever, and Holmes suspects murder.

Mrs Warren, a London lodging-house keeper, comes to Holmes with a curious story of a reclusive and eccentric tenant. Mrs Warren's husband has been abducted and then quickly released again, perhaps a case of mistaken identity. Holmes decides the case is more important than it appears.

When Susan Cushing first consults Holmes about the disappearance of her sister Mary, he shows little interest in the case. But then, at Christmas, Susan receives an alarming present in a cardboard box, and Holmes is quickly on the trail of a dangerous criminal.

Holmes is approached by Helen Stoner, who feels threatened by her domineering step-father, Dr Grimesby Roylott. Her sister died mysteriously just before her planned wedding, and Helen has heard again the curious whistle she first heard on the night of her sister's death.Holmes perceives great danger and lays a complicated plan to defeat the threat to the beautiful Helen.

The French government sends for Holmes when the Mona Lisa is stolen from the Louvre. Holmes swiftly decides he is dealing with a mastermind - and none other than his old enemy Professor Moriarty himself.Holmes foils Moriarty's plans to sell Leonardo da Vinci's masterpiece and trails him to Switzerland, where they meet and fight to the death above the famous waterfall at Reichenbach.

In a remote area of Dartmoor, The Silver Blaze, England's most famous and valuable racehorse, goes missing, the dead body of the horse's trainer is found, and sheep are savaged. The Police seem bewildered, but then they charge Fitzroy Stephen, a famous figure in the racing world, with the murder. Holmes is called in to trace the missing horse and finds he has to separate fact from fiction.

A notice in a newspaper seeks red-headed men, inviting them to join a league which will pay them well - and Jabez Wilson, a pawnbroker who responds, finds he is hired and paid generously for spending four hours a day copying an encyclopedia in long hand. When the league is suddenly dissolved, Holmes is asked to find out what has been going on, and he quickly suspects crime. Indeed, behind this curious arrangement lurks Holmes's arch-enemy, Professor Moriarty.

Holmes is curious about a series of attacks on figures of the French Emperor Napoleon Bonaparte around London. One such incident leads to a violent death, and he investigates. Lestrade sees an Italian connection and proposes to focus Scotland Yard's attention on the Italian quarter of London, but Holmes is more interested in Chiswick.

A young solicitor, John Hector McFarlane, seeks Holmes's help after retired builder Jonas Oldacre dies in a fire. McFarlane, who benefits from Oldacre's will, is suspected of murder and asks Holmes to clear his name. Holmes looks for another motive and another killer, and dresses up as a tramp to get the information he needs about the Oldacre household. The surprising answer he finds is that Oldacre is not exactly dead.

An obscure family document containing an enigmatic ritual holds the key to a hidden treasure if Holmes can decipher the mystery.

Neville St Clair works in the City of London and is a man of very regular and respectable habits. One day, his wife goes into town for lunch and is shocked to see her husband in the window of an opium den. That evening, he fails to return home, and Mrs St Clair decides to consult Holmes.

The police are baffled by the murder of Willoughby Smith, and Inspector Hopkins looks to Holmes to solve the case.

A plumber, John Horner, is arrested just before Christmas and charged with stealing a famous jewel, the Blue Carbuncle, from Lady Morcar. He denies the theft - but he has a criminal record, and all the evidence is against him. After Holmes's doorman finds the Carbuncle in a Christmas goose, Holmes uses an old hat to track the goose to a poultry dealer, then traps the servant who stole the jewel and framed the plumber. The Blue Carbuncle has a dark history, and the stone features in the programme's opening credits with turbulent scenes from its past.

Dr Trevelyan calls on Holmes on behalf of his friend Blessington, after a Russian father and son vanish during a consultation. Blessington knows of no one who wishes him ill, but he is found hanged the next day. Holmes investigates, with advice from Watson.

Colonel James Damery calls on Holmes when the rich and beautiful Miss Violet Merville announces her engagement to Baron Gruner, a dangerous Austrian. Gruner has persuaded Violet that he is not a killer, and Holmes has to establish the truth and foil the powerful baron.

Hilton Cubitt, from Derbyshire, consults Holmes about a series of dancing men picture-messages his wife is receiving. On their wedding-day, she had made Cubitt promise he would ask her nothing about her past, but she now seems to be terrified. Holmes has to decipher the code of the matchstick men and get to the bottom of a dreadful murder which lies behind it.

Holmes is called in to investigate a murder. Lady Brackenstall says she saw a gang of men kill her bullying husband, Sir Eustace, but on Holmes's arrival the case seems to have been solved. Holmes is uneasy and returns to the scene of the crime, where he finds things are not as they appear to be. And Watson is curious to hear about the lady's love affair with a sea captain during a long voyage.

The Duke of Holdernesse needs Holmes's help when his son, Lord Arthur Saltire, is kidnapped from the Priory School. Holmes finds the connection between an old mystery and a teacher who has also gone missing.

A masked man calls, on confidential business, and Holmes quickly recognizes the visitor as the King of Bohemia. The King is planning for himself a dynastic marriage and is worried about a compromising photograph in the possession of his American former mistress. He wants Holmes to get it back for him.In outwitting the lady, Irene Adler, Holmes goes to great lengths - and at the end of the affair Watson comes to the conclusion that his friend is himself smitten.

Holmes is approached by Percy Phelps, of the Foreign Office, to recover a document which has been stolen - before it can cause an international scandal and ruin Phelps's career. It seems the British Empire and the Kingdom of Italy have entered into a secret and embarrassing treaty.

Three years on from Holmes's fatal fall into the Reichenbach Falls, Watson wrestles with a murder case under his own steam. But who is the enigmatic stranger in the Coroner's court, listening intently to all the evidence? Holmes returns home and explains how he escaped death at Reichenbach, while Moriarty lost his life. Holmes and Watson must now bring a partner of Moriarty's to justice, by proving he is a murderer.

Reluctantly, after an illness, Holmes takes a holiday in Cornwall, with Watson for company. Then one day he finds himself investigating a mysterious death... after a quiet evening at home playing cards, three local inhabitants have been found in the morning in a terrible way: the two brothers overtaken by sudden mental illness, babbling incoherently, and their sister dead, with her face twisted into a look of terror. Holmes is delighted with the chance to bury his holiday boredom by taking on the case.