The Major's Asylum

AU Many Happy Returns. John is grieving Sherlock's death, when Mycroft and Greg reveal to him a video made 10 years before his and Sherlock's supposed first meeting. John learns that he has had Pyschogenic Amnesia since the fire fight in Afghanistan that invalided him, and begins to remember the last case MI6 detective consultant Sherlock Holmes was working on. One Major Sholto's.