Setup" (Part 1) -- Castle and Beckett investigate the apparent robbery-homicide of a New York cab driver, only to discover that the victim was involved in a mysterious conspiracy with unimaginable consequences. As the stakes continue to rise, hard-charging federal agent Mark Fallon (guest star Adrian Pasdar) takes over the investigation. Together, Fallon, Beckett and Castle must race to unmask the truth about the victim before it's too late