It turns out that Atatalanta and Hippomenes are a Greek couple living in a neighborhood in Madrid who are not very well off financially. They agreed to collaborate with us in exchange for a reduction of their sentence.
The shadow contacted them to offer them a large amount of money for posing as workers of the royal palace and the prado museum. They did not know her at all, nor did they see her face, she only sent them a message with the instructions they had to follow and an advance payment that convinced them. On the way out of the museum, they heard him talk on the phone and mention the bank of Spain, a gold chamber and that he was going to enter through the door that was not guarded 24 hours a day.
We spoke with the director of the bank, and he told us that the bank had stored gold coins from different periods, which are priceless: doubloons, ducats, maravedis… But that chamber was impossible to steal, and that all the doors have guards 24 hours a day.
Maybe the shadow was referring to another type of guards, what number is it?
*The key must be written in lower case and without accent.