In 18 seasons, "Law & Order" has cycled through a couple dozen actors in lead roles. So the latest change is just business as usual.
But Jesse L. Martin's last episode as one of the show's stars coincides with Anthony Anderson's first episode as one of the show's stars. And that is something out of the ordinary.
Then Anderson's Fox show, "K-ville," was canceled, making him available for "Law & Order." He signed on during the writers' strike, and once the strike ended, his entrance and Martin's exit were orchestrated.
No matter how closely you've watched over the past nine seasons, you're still in for some surprises about Martin's character, detective Ed Green.

Green shoots and kills a suspect. Detective Kevin Bernard (Anderson) is one of the internal affairs detectives assigned to investigate Green's actions. In Green's final episode, the police detective becomes the suspect. And without giving too much away, there are some believable twists that turn this case into something other than it at first appears.
Which is sort of business-as-usual for "Law & Order."
It's not giving away anything, however, to tell you that Green will be exiting, leaving an opening for a new homicide detective. Nor is it a secret that detective Bernard will be that replacement.