This happened after the Ishbar Civil War, when the Flame Alchemist Roy Mustang had just been promoted to lieutenant colonel and was still in the Eastern City. It was also the first mission assigned to Mustang by Second Lieutenant Lisa Hekoai, Warrant Officer Jane Haberk, Warrant Officer Heymans Breda, Sergeant Walter Farman, and Sergeant Ken Fili.
RR Xiang, Mustang Team, actually published it elsewhere a long time ago... Take it here and try it out.
Conception: