When David is summoned to another world to become a hero, he is quickly branded the weakest candidate, with a seemingly useless skill called Absorption that does nothing.

Kicked out of the Institute of Magic and Training, he hires high-level adventurers to guide him, but he is immediately duped and thrown into the lowest level of a cursed dungeon, an S-Class labyrinth containing monsters and creatures from the deepest parts of hell.

Left to struggle and fend for himself, he soon discovers his Absorption skill isn't as useless as he thought. He is able to steal and copy the powers of any monster or creature he bites, eventually gaining abilities such as brief indestructibility, fire breath, ice touch, super speed, and more.

And after completing a quest to escape, he ventures back to the institute, seeking revenge on all those who wronged him, while occasionally returning to the dungeon to gain new powers and abilities in preparation for the coming apocalypse on the Kingdom.