During the construction of a new district of Brighton, a decomposed corpse is found in an abandoned tunnel. Roy Grace and his team of forensic experts take on the investigation. Based on the dentures, it is possible to determine that the deceased woman is the wife of the man who died on September 11, 2001 at the World Trade Center in New York. It would seem that we can put an end to this, but Grace, an experienced detective, feels that the case is not finished and is not as obvious as it looks at first glance...