The body of a man is found in open countryside. No fingerprints in the files, no identity papers, no search warrants, and a swollen face. Darius, Marijo, Ben and Duchess are called to the scene of the crime: it is indeed an "Invisible", a body without identity. It is up to them to find that of this man, and to get their hands on his murderer. And this, within 7 days. In which case, the man will be thrown into the common grave.
