It is loosely based on the comic book series The Extraordinary Adventures of Adèle Blanc-Sec by Jacques Tardi and, as in the comic, follows the eponymous writer and a number of recurring side characters in a succession of far-fetched incidents in 1910s Paris and beyond, in this episode revolving around parapsychology and ultra-advanced Ancient Egyptian technology, which both pastiche and subvert adventure and speculative fiction of the period.

In Paris, c. 1912 Professor Espérandieu is experimenting with telepathic techniques, and he unintentionally hatches a 135 million year-old pterosaur egg within the National Museum of Natural History.

This results in the death of a former prefect (scandalously sharing a taxicab with a Moulin Rouge showgirl) which, though witnessed only by the then-drunk passerby Ferdinand Choupard who is detained by the police, sparks an epidemic of claimed sightings of the creature.

The President of France orders the case be considered of utmost urgency by the National Police, only for it to be handed down to the highly decorated but bumbling Inspector Albert Caponi.

Adèle Blanc-Sec, a journalist and travel writer of some fame, finds herself involved after returning from Egypt, where she was searching for Ramesses II's mummified doctor/physician Patmosis.

Her mission is complicated further by Espérandieu being on death row, having been blamed for the pterosaurs attacks, in lieu of Inspector Caponi and celebrity big game hunter Justin de Saint-Hubert having any success in taking down the beast itself.

The film incorporates characters and events from several of the albums, in particular the first, "Adèle and the Beast", first published in 1976, and the fourth, 1978's "Mummies on Parade,"[2] within an overall plot of Besson's construction and takes place primarily in Paris, c. 1912.