Lina Inverse and Gourry Gabriev travel to the town of Acassi, known for its tasty octopus. However, the octopus meat is cursed, causing the person who eats it to only be able to speak takogo (タコ語, octopus language). Sorcerers and sorceresses cursed by this also cannot cast spells, since the spells have to be spoken in the common language in order to work.

Gourry just happened to eat one of those cursed octopi (after fighting for it with Lina), which now caused him to speak in takogo. This often caused very hilarious and awkward situations during the film (the phrase "Great God Almighty" was translated into "Flat Chested", which offended Lina greatly). But soon, everyone in the town began to speak takogo, even though they haven't eaten octopus - including Amelia and Zelgadis, who had just arrived in town. Xellos is also there... and he seems to know what's going on... but he's not telling.

It soon became evident that the octopi had planned to use the accumulated anger from the villagers of Acassi to release a demon that was sealed many years before. Lina and friends have to stop these plans before they came to fruition. However, it becomes complicated when Lina is infected with the takogo affliction, which negates much of her magic... including the Dragon Slave!

-Wiki