In "A Study in Scarlet", John Openshaw was poisoned with strychnine, which caused violent convulsions and a rapid death.

In "The Hound of the Baskervilles", the mysterious hound that haunted the Baskervilles was known as Black Shuck, a legendary spectral dog associated with death and misfortune.

In "The Sign of Four", Watson and Holmes were hired to recover the Agra Treasure, a collection of valuable jewels and artifacts stolen from India.

In "The Valley of Fear", Holmes and Watson went undercover to infiltrate the Moriarty Gang, a powerful criminal organization led by Professor Moriarty.

In "The Adventure of the Speckled Band", Julia Stoner was killed by an Indian cobra, which was hidden in a ventilator shaft and controlled by her stepfather.

In "The Adventure of the Dancing Men", the criminals used the Pigpen Cipher, a simple substitution cipher, to communicate their plans.

In "The Adventure of the Empty House", Holmes faked his death by using a wax figure that resembled him and leaving it in his study.

In "The Adventure of the Final Problem", Holmes and Moriarty fought at Reichenbach Falls in Switzerland, where Holmes seemingly fell to his death.

In "The Adventure of the Norwood Builder", Holmes discovered a secret tunnel that connected the house to a nearby quarry, which was used by the criminals to transport stolen goods.

In "The Adventure of the Three Students", the murders took place at Cambridge University, where Holmes and Watson investigated the deaths of three students.

In "The Adventure of the Golden Pince-Nez", a valuable artifact known as the Golden Pince-Nez, a pair of gold-rimmed eyeglasses, was stolen from a museum.

In "The Adventure of the Six Napoleons", the busts of Napoleon were created by the famous sculptor Auguste Rodin.

In "The Adventure of the Three Gables", a secret society known as the Priory of Sion was involved in the murders and the search for a hidden treasure.

In "The Adventure of the Red Circle", Holmes and Watson investigated a criminal organization known as the Red Circle, which was involved in smuggling and other illegal activities.