There's a serial killer on the loose marking all of his victims with a Y on their chests and one or more of the csi's lives are in danger in this season 5 finale
Quest roles:
David Lee Smith(Rick Stetler), Brendan Fehr(Dan Cooper), Johnny Whitworth(Jake Berkeley), Monet Mazur, Taylor Handley, Daniella Alonso, Logan Grove, Michael Kelly(Lucas Wade), Wynter Kullman(Rita Bolton), Chelsey Crisp(Shelly Seaver)