At around 6am last Thursday, fishermen at La Ñora beach in Gijón spotted a woman walking around aimlessly along the shore.
She was barefoot, had a superficial wound on her forehead and no idea of who she was.
There were no signs that she had been physically attacked or robbed, as she had €50 ($68) in her pocket, but Civil Guard police were unable to identify her as she was not carrying any identification.
Staff at the local Cabueñes Hospital where she was taken for a medical check-up said she spoke fluent English, but also understood French and Spanish.
The woman, who appeared to be around 25 years old, appeared to have no knowledge of who she was or where she was from.
The only clue she had been able to provide the local authorities with was that she remembered catching a train and a bus from the nearby town of Oviedo to reach the beach.
One of the few clues local police had is a message written on her wrist in English: "Sorry, I failed".
Even though local and national media had been told to give coverage to the story, Spanish Civil Guard Police did not receive a single call from anyone claiming to know the mystery woman for several days.
As she wasn't a missing person and hadn't been legally incapacitated , local authorities were unable to release a photo of her.
Now, however, her identity has been revealed after joint efforts by European police forces: she is a 24-year-old French woman from Toulouse.
The woman who had been missing since February 11th was doing Erasmus in Slovakia and had been travelling around Spain, El Mundo reported on Tuesday.
It is still not known why she couldn't remember how she had come to be on the beach.
However, her family say she had left a letter to a friend containing a similar apology to that written on her wrist when she was found. The family added the woman had been robbed in January, and had been feeling unwell ever since.