Inspector Lestrade was on the verge of capturing a fugitive he had been chasing for over a year when he received a text from Sherlock: "Save me." Gritting his teeth, Lestrade abandoned the arrest and rushed back to 221B Baker Street, only to find Sherlock distressed about John's wedding. John had asked Sherlock to be his best man, a role which required delivering a speech at the ceremony—a prospect that filled Sherlock with dread.
Mrs. Hudson brought Sherlock his morning tea and tried to comfort him by saying that marriage can completely change a person, which only made Sherlock feel worse. As Sherlock remained visibly tense in the lead-up to the wedding, Mary suggested that John find him a few cases to distract him.
The wedding proceeded as scheduled. A bridesmaid flirted with Sherlock, but he remained unmoved. A man named David appeared at the wedding, and Mary seemed pleased to see him. However, David kept his distance—because Sherlock had previously investigated him and warned him to never show any affection toward Mary unless John was present. Sherlock's threats had left David thoroughly intimidated.
John was pleasantly surprised when his old commanding officer, Colonel Sholto, arrived at the wedding. When the time came for the best man's speech, Sherlock spoke with sincerity and genuine emotion. He was deeply moved—even stunned—to be named by John as one of the two people he loved most and referred to as his best friend. The guests were visibly touched by Sherlock's words.
Sherlock then went on to share amusing stories about John, most of which involved their adventures solving crimes together. In case after case, John had demonstrated courage, decisiveness, and unwavering loyalty. Sherlock recalled how, during the mysterious death of a Guardsman, John had shown the professionalism of a military doctor, leaving a strong impression on him.
For John's stag night, Sherlock and John had gone out and gotten thoroughly drunk on the streets, eventually requiring Lestrade to bail them out of jail. That night also involved the "Ghost Dating" case, where several women had gone on dates with a man who later mysteriously disappeared. At first, Sherlock hadn't connected that case to another investigation. But during the wedding toast, it suddenly clicked: someone was planning to assassinate Colonel Sholto at the wedding. Thinking quickly, Sherlock intervened and thwarted the attempt, allowing the celebration to continue uninterrupted.
John and Mary danced gracefully to Sherlock's beautiful violin music, while Molly and her boyfriend hugged happily. The post-wedding party carried on lively and crowded, but Sherlock quietly put on his coat and slipped away alone into the night.