When Erin’s informant is murdered, she blames herself and works to help Danny discover who killed him.

When Beckett and her team burst into an apartment on a murderer’s trail, they see Castle standing over a dead woman’s body holding a gun; Beckett arrests Castle as he…

A reformed drug addict with everything to live for is found dead in an alley. The CSI’s discover he was the victim of a premeditated plot.