Mary Watson (née Morstan) was the wife of Dr John Watson. She is first introduced in The Sign of Four and Watson refers to her in a number of the stories. While she is generally not involved in the main action of most stories, she is a central character in The Sign of Four. Mary's father, a senior captain of an Indian regiment and later stationed near the Andaman Falls, disappeared mysteriously in 1878, a fact which would prove to be related to the mystery in The Sign of Four. Mary Morstan is Holmes' client in this story, and Watson describes her at their first meeting this way: