A solitary elf named Snail treks through deadly dungeons, snowy peaks, and deep caverns on a secret mission. She is the one responsible for placing all those treasure chests that adventurers find scattered throughout the world. Her job is to carefully deposit these chests in dangerous locations—from high grass in starting forests to the lairs of terrible monsters—so that heroes can find the items and equipment they need to survive.

Snail is an ancient and incredibly powerful elf who rejects magic, preferring to solve problems with her sword. She dispatches legendary threats like ancient dragons and sea gods with casual ease, treating them as minor obstacles in her delivery route. Despite her cold efficiency in battle, her daily life is surprisingly peaceful. After placing a chest, she often stops to cook meals from the monsters she has slain, enjoys a cup of coffee while watching the sunrise, or shares the company of her unusual companion, a mild-tempered and regenerating slime that is also apparently delicious.

The world of Dungeon Elf is heavily inspired by classic Japanese role-playing games. Locations are given difficulty ranks, and monsters have specific encounter rates, though the story often explores the deeper history behind these game mechanics. Snail walks through ruins of ancient, technologically advanced civilizations and encounters horrors inspired by the work of Junji Ito. While the early narrative is episodic, following Snail as she explores a new location and faces a new boss in each chapter, it establishes a relaxing and atmospheric tone rather than a high-stakes adventure.

As the series progresses, hints of a larger mystery emerge. Snail's purpose is questioned: is she an altruistic helper, a chaotic trickster, or something else entirely? The story slowly reveals more about the forgotten history of the world and the role Snail plays in maintaining its balance, all while she continues her solitary work, unnoticed by the adventurers she helps.