The Adventure of the Cheerful Four both the puppets of Jonathan Small and Arthur Morstan have the atmosphere of the members of a famous British musical band. One night Arthur Morstan, a pupil of Archer House is attacked and gets injured. His younger sister Mary Morstan requests Sherlock Holmes to solve why his brother is attacked while John H. Watson falls in love with her. They began searching Arthur's room with the help of Abdullah, roommate of Arthur. Holmes suspects that the offeder stole into the room from skylight and he and Mary find small handprints around it on the roof. Watson tries to get up
Minor Sherlock Holmes characters to propose to her. She is described as blonde with pale skin. At the time she hires Holmes she had been making a living as a governess. Although at the end of the story the main treasure is lost, she has received six pearls from a chaplet of the Agra Treasure. Her father, Captain Arthur Morstan, was a senior captain of an Indian regiment and later stationed near the Andaman Islands. He disappeared in 1878 under mysterious circumstances that would later be proven to be related to the mystery, "The Sign of the Four". Her mother died soon after her