The Flame Alchemist, The Bachelor Lieutenant, and the Mystery of Warehouse 13

In the opening segment, someone orders the Mustang unit to keep tabs on their own leader. Havoc enlists Falman, Breda, and Fuery to document the colonel's movements, only to be crushed when their notes show Mustang taking his latest girlfriend to a play. In the second and longest part, Mustang, unaware Havoc's failures are his own doing, tasks Falman with finding the lieutenant a well-adjusted beauty. While Sheska takes provisional work recreating destroyed files for Archer, secretly hoping to find a lead on Hughes' death, she runs into Falman, and Major Armstrong overhears and suggests his own unmarried sister Catherine.

At the Armstrong mansion Havoc is intimidated by the imposing family, then meets the comparatively plain and shy Catherine. He works up the nerve to ask her out but is rejected, since she only fancies men like her brother Alex, and faints from embarrassment. In the final segment, Falman and Fuery spot a number thirteen glowing on a warehouse door and, with Breda, spin a ghost story about past executions. Mustang reluctantly agrees to investigate with them at night, stopping first at the Hughes home, where Winry watches him coldly from a window.

Sheska finishes her report, which Archer promptly orders destroyed over her objections; he then wins the Führer's approval to march on Reole with Kimblee and Tucker. That night the men find the ominous thirteen is merely a partly obscured warehouse letter B, and freshly dug earth they take for a murderer's work turns out to be Hawkeye's dog Black Hayate burying bones. Afterward Mustang secures the Führer's permission to join Archer and Armstrong in suppressing the Reole uprising.

The Mustang unit surveils their commander at someone's orders. Mustang assigns Falman to find Havoc a partner, leading to a failed match with Catherine Armstrong. Sheska recreates files for Archer while secretly pursuing Hughes' death, and Archer destroys her report. The warehouse mystery is solved as a misread letter and Black Hayate's buried bones. Archer gains approval to move on Reole with Kimblee and Tucker, and Mustang arranges to join the mission.

The three segments adapt separate sources: the opening from a bonus chapter on Mustang's observation diary, the matchmaking portion from a bonus chapter on the second lieutenant's battle, and the warehouse story from a mini-tale in the first novel, The Land of Sand. It is the only episode of the series in which neither Edward nor Alphonse appears. Rather than Al, Hawkeye narrates the opening, and the customary photo shows the Mustang unit with Armstrong and Hughes in place of the Elrics.