[1] As the episode begins, two burglars ransack the house of Irene Adler, a young and beautiful lady.
The king is due to marry a young Scandinavian princess, and if the photograph becomes public, the marriage would be called off.
He learns that Adler has a regular visitor, a lawyer named Godfrey Norton of the Inner Temple.
Holmes conceives a plan involving him dressing up as a clergyman, staging a fight and then having Watson, using a plumber's smoke rocket, convince Irene Norton (née Adler) to reveal the location of the photograph.
She has left in the secret compartment a different photograph, this one of herself alone, and a letter addressed to Holmes, saying that she had tailed him dressed as a man.