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'.

In a series of escalating encounters, former security guard David Dunn uses his supernatural abilities to track Kevin Wendell Crumb, a disturbed man who has twenty-four personalities. Meanwhile, the shadowy presence of Elijah Price emerges as an orchestrator who holds secrets critical to both men.

An ordinary man makes an extraordinary discovery when a train accident leaves his fellow passengers dead — and him unscathed. The answer to this mystery could lie with the mysterious Elijah Price, a man who suffers from a disease that renders his bones as fragile as glass.