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 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.

Violet Hunter consults Holmes about Edward Rucastle's offer of a job. He wants her to cut off her hair before coming to work for him as a governess. Holmes sees a sinister motive and investigates.

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.