Two naval officers go to a home where they may find evidence of classified documents that were stolen from the Spanish Admiralty, probably by someone working at the Admiralty's offices in Madrid. The suspect assaults the officers, killing one and disabling the other, locking him in a closet before fleeing.
Within minutes the surviving officer manages to escape from the closet and leave the house, and as he leaves he notices a young woman looking out the second-floor window of the house next door. He immediately enters the house and speaks with the young woman, who is the only witness who could have seen the killer as he left the house.
An elaborate plot is hatched that may force the killer to identify himself. The young woman is brought to the Admiralty and taken to a room where IDs of all employees are projected, one after another, on a screen. The Admiralty's coffee lady brings in coffee, glancing at the screen just as the witness comments on an image, then leaves the room. Admiralty employees have not been told who the young woman in the room is, or her reason for being there, but once the coffee lady has left the room one of the officers tells the witness that word will soon spread; the coffee lady is the biggest gossip at the Admiralty.
Oh, I forgot to mention something critical to the plot, but you'll find that out for yourself very early in the film.
Think "deception."
