Just right after the events of SA, the Moriya Shrine holds a party where almost all characters are included. The main characters read an article on Aya's Newspaper about the Scarlest Mist Incident, which happened during Embodiment of Scarlet Devil. Remilia feels nostalgic and Sanae wants to know how Reimu solved this incident. Marisa and Sakuya then decide to tell the story. The rest of the episode is focused on the events of EoSD. However, the plot is different in several things, such as Aya telling Marisa to gather information from Scarlet Devil Mansion in the first place, or Marisa directly battling against Flandre, and Patchouli afterwards. According to one of Patchouli's dialogues, Reimu is inside SDM at the same time she's battling against Marisa. After the credits, Manpuku Jinja announces Reimu will battle Sakuya and Meiling in the third episode.
本集开始于东方原作《东方地灵殿》时期在守矢神社大摆宴席的场景。大厅内挤满了众多东方角色，囊括了《地灵殿》之前的绝大多数角色。其制作之大，震撼非常。遭灵梦打伤的早苗刚一进屋，灵梦便对她发起了酒疯。鸦天狗四处派发过期的报纸：《主犯蕾米莉亚即日KO！！！》这是有多过期啊！的头条新闻勾起了大伙对幻想乡红雾异变的回忆。
开场动画是之前发行的《地灵殿》PV《丛云映月花随风》。在这之后，故事终于从魔理沙的落语らくご（一种日本单口曲艺表演）中开始了。
《红雾异变之章》较为巧妙地将《红魔乡》原作对半分摊到灵梦和魔理沙两人身上。魔理沙一开始便遭遇了最强对手的挑衅。之后在射命丸文的怂恿下闯入红魔馆（文未在原作《红魔乡》出场）。魔法使进入内室，遇到了长期幽禁在闺房的芙兰朵露·斯卡雷特。两人“玩耍”正酣时，红魔馆的主人释放了遮天蔽日的红雾。帕秋莉·诺蕾姬阻止了芙兰的胡闹，一言不合就对魔理沙开打。最终，芙兰在心灰意冷中目睹魔理沙被帕秋莉的弹幕吞噬。主角阵亡，全剧终。
片尾曲为「ヒトリシズカ」（原曲：东方红魔乡露米娅角色曲「妖魔夜行」）。片尾剪纸风格的插画作者为Tsubameyado[2]，接下来红雾异变和花之异变所有剧集的片尾插画都是他绘制的作品。
