Sherlock struggles to deliver the best man's speech at John and Mary's wedding reception; Sherlock tells the guests about past unsolved cases and inadvertently stumbles upon the identity of the murderer and his next intended victim.
Sherlock investigates Charles Augustus Magnussen, a master blackmailer who knows the weaknesses of every prominent figure in the Western world; in his pursuit of clues, Sherlock makes a discovery about Mary that threatens her future with John.
Sherlock Holmes and Doctor Watson investigate a mysterious ghostly bride who appears to have committed murder from beyond the grave.
