The exploits of the Los Angeles–based Office of Special Projects (OSP), an elite division of the Naval Criminal Investigative Service that specializes in undercover assignments.

The exploits of a group of men and women who serve the City of New York as police officers, firemen, and paramedics, all working the same fictional 55th precinct during the 3pm to 11pm shift - the 'Third Watch'.

Exasperated at being stuck on a piano Rhapsody he's been writing for seven years, Sol pushes himself over the edge, having an hallucination of a mysterious young woman. Soon, Sol discovers that he has brain tumors, and a risky operation is his only means of survival. Initially deciding to go through with the surgery, things change when he meets Sofia, the woman from his vision. She urges Sol not to have the operation because the tumors aren't what they seem. Unable to fathom her strange appearance, he starts out to discover the nature of these events - unearthing what The Rhapsody really is.

When a law student uncovers chilling secrets and places her life at risk, a bitter, rough-around-the-edges detective gets assigned to her case.