Fire Emblem: Monshou no Nazo is the third game in the Fire Emblem series. It was originally only released on the SNES and Super Famicom in Japan but then was ported to the Wii Virtual Console and the WiiU Virtual Console. It is made by Nintendo and rated E10+ on the Wii and WiiU.
Monshō no Nazo drops many of the gameplay elements introduced in Fire Emblem Gaiden, such as explorable towns and a navigable world map. However, it does carry over certain features; such as a battery RAM save feature and the use of icons for weapons along with their names. The game's most prominent new feature is the dismount command, which allows cavalier units to get off their horses and fight on foot. The limitation to this factor is that cavaliers can only wield lances when on horseback and swords while on foot. Furthermore, cavalier and airborne units are forced to dismount in chapters that take place in interior locations.
The game takes place in the fictional continent of Archanea, which originally appeared in the first game of the series. The countries include Archanea, Dolhr, Macedon, Grust, and Khadein.
- Marth (マルス Marusu?) is the protagonist of the game, Prince of Altea. He is 16 years of age and a descendant of the hero, Anri, who once defeated the dark dragon Medius with the divine sword, Falchion.
- Sheeda (シーダ Shiida), the heroine of the game. She is the princess of the island Kingdom of Talis, and Marth's fiancee in Book 2. She appeared in Super Smash Bros. Brawl as a sticker, listed in the official site under the name "Shiida."
- Jagen (ジェイガン Jeigan?) is a veteran knight of Altea, and a retainer of Prince Marth. In Book 2, he has grown older and is no longer capable to fight in battle. Instead, he becomes Marth's tactician to replace Malledus, who has fallen ill.
- Abel (アベル Abel?) is a knight of Altea, nicknamed the Black Panther. His partner is Cain.
- Nyna (ニーナ Niina?) is the Princess of Akaneia and the last surviving member of the royal family, following the slaughter by Doluna. She is rescued by Camus and eventually finds refuge in the hands of Hardin's army, which is known as the Knights of Orleans. She entrusts her family's treasure, the Fire Emblem, to Marth. She marries Hardin in Book 2 because Akaneia needs a king, but her feelings for him were only platonic. In reality, she is in love with Camus.
- Malledus (モロドフ Morodof?) is Marth's elderly tactician in Book 1. He explains to him the events of Anri's war with Medeus. During Book 2, he becomes ill, and Jaigen takes his place.
- Hardin (ハーディン Hardin?) is the Prince of Orleans and the king's brother. When Marth first meets him in Book 1 he is a stubbornly honorable man, and one of the few people in Orleans who still willingly protects it. He shortly joins Marth's cause to defeat Medeus. However, in Book 2 he is one of the main villains. He was deeply in love with Nyna and married her, becoming the King of Orleans. But after discovering she didn't love him, Hardin became heartbroken and locked himself in his room, not allowing anyone to see him. Taking advantage of this, the evil priest Gharnef used the dark orb to possess Hardin. However, Marth wasn't able to save him without killing him. In his last moments, Hardin thanked Marth for freeing his soul from Gharnef's dark orb, and asked him to take care of Nyna in his stead.
- Sirius (シリウス Sirius?), a masked knight who is actually Camus. He was previously presumed dead at the hands of Marth, after the events of Book 1, but somehow survived.
Marth is the prince of Altea and a direct descendant of Anri, the warrior who slew the dark dragon Medeus. However, after an attack from the neighboring kingdom of Doluna, Marth is forced to become an exile in the neighboring nation of Talys. His sister Elice is taken hostage after their father is killed battling the evil priest Gharnef. With the help of Altean knight and his mentor Jaigen, the Princess of Talys, Sheeda, and others, Marth embarks on a quest to find the sacred sword known as Falchion. Only then will he be able to confront Gharnef and the resurrected Medeus, win the kingdom of Altea back, and rescue his sister. Along the way, Marth learns of Medeus' connection to the ancient Manakete tribe, able to transform into dragons using special stones, and that Medeus is the king of the last remaining dragon tribe. In the end, Marth defeated Medeus and restored peace.
In the new second book of Monshō no Nazo, Hardin, former Prince of Aurelis and ally to Marth in Book 1, ascends to become Emperor of Akaneia. However, Marth smells a rat as 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 the forces of darkness at work again as Lang, Hardin and his forces become corrupt. Marth soon also learns that the Dragon King Medeus is still alive. Tracing an old legend of yore, Marth retrieves the Fire Emblem once again (this time from Linde, who was entrusted with it by Princess Nyna), and goes on a quest to retrieve the twelve star orb shards to revive the shattered Star Orb. All the while, having been branded a traitor by King Hardin, Akaneian forces hunt his allies relentlessly, all the way to the desert of Khadein. Finding out from Boah that a depressed Hardin was turned evil with the dark orb by Gharnef in the form of a merchant and only the light orb can save him. When the Sage Gato assists him on his quest, 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 Akaneia to liberate Altea, to save Hardin and his sister. Sadly Marth isn't able to save Hardin from the Dark orb without killing him in the process. After Hardin dies, two special chapters are unlocked, and Marth and his allies discover where the new incarnations of Medeus and Gharnef are residing. Gharnef again holds the Falchion sword, and using the Starlight magic, Gharnef is defeated, and Marth confronts Medeus, who has now taken the form of a dark dragon. In the final confrontation, Medeus holds captive Sirius's love interest Nyna, Minerva's younger sister Maria, Julian's lover Lena, and Marth's sister Elice.
Books One and Two feature different soundtracks. The recruit theme in Book Two is a classical version of the one in Book One. There has been manga written on the first map of the first book.
On release, Famicom Magazine scored the Super Famicom version of the game a 24 out of 40, however Monshō no Nazo was popular enough to hold the No. 1 position on the Famitsu chart for one year. In 2006, Monshō no Nazo was the only Fire Emblem game which appeared in the top one hundred games list from readers of the magazine Famitsu, holding the sixty-eighth place.