Fire Emblem: Monshou no Nazo (Mystery of the Emblem) is the third game in the Fire Emblem series and the first released on the Super Famicom on January 21, 1994. The game is comprised of both a remake of the original Fire Emblem: Ankoku Ryu to Hikari no Tsurugi and a sequel storyline that once again focuses on Prince Marth of Altea. Monshou no Nazo was released on the Japanese Virtual Console in December of 2006. In 2010, a remake of Monshou no Nazo was released in Japan for the Nintendo DS. Unlike Fire Emblem: Shadow Dragon, the DS remake of the first game, Shin Monshou no Nazo was never released outside of Japan.
The first part of the game, Book One, retells the story of Fire Emblem: Ankoku Ryu to Hikari no Tsurugi. However, the story is condensed, and so not all of the events and characters that appeared in the original Famicom release appear in this version. The first game's DS remake, Fire Emblem: Shadow Dragon, retells the original game's story in its entirety.
In Book Two, Hardin, prince of Aurelis and ally of Marth in the original storyline, ascends to the throne. Hardin's military begins to occupy neighboring countries by force, and Marth and his army are used to conquer smaller countries under orders of General Lang. Marth soon discovers that the forces of darkness are at work again, corrupting Lang and Hardin, and that Medeus is still alive. Marth retrieves the Fire Emblem once again (this time from Linde, who was entrusted with it by Princess Nyna), and embarks on a quest to retrieve the twelve shards of the Star Orb in order to revive it. Branded a traitor by King Hardin, Marth and his forces are hunted down all the way to the desert of Khadein. There, Marth learns that a depressed Hardin was manipulated by Gharnef and only the Light Orb can save him. Marth journeys through the icy mountains to obtain the Light Orb, required to defeat and free Hardin.
With the Light Orb, Marth and his allies stage a final assault on Archanea to liberate Altea and save Hardin and Elice. Though he is able to rescue Elice, Hardin cannot be saved, and he dies. Following Hardin's death, the location of Medeus and Gharnef is revealed. After defeating Gharnef for the final time, Marth confronts Medeus, who has now taken the form of a dark dragon.
As a partial remake of the original Fire Emblem, Monshou no Nazo introduces a number of gameplay elements that weren't present in Ankoku Ryu to Hikari no Tsurugi. For example, mounted units such as cavaliers and pegasus knights could dismount and move on foot. Book Two also introduces Zodiac items that are scattered around the continent. Characters in possession of Zodiac items at the time they level up experience altered stat growth depending on which item they have equipped.
Monshou no Nazo was adapted into a two-episode anime that spans the earliest chapters of the game. The plot chronicles Marth's escape from Altea, his defense of Talys from pirates, and the rescue of the cleric Lena from mountain bandits. The anime was published on VHS in North America by the distributor ADV under the title Fire Emblem in both English dubbed and subtitled formats.