Joe Mantegna, A.J. Cook, Kirsten Vangsness and Aisha Tyler are among the returning stars for the update.
The revival series will return six original cast members, but who's not returning?
It's the end of an era! ET exclusively debuts a sneak peek from Wednesday's two-hour swan song.
Showrunner Erica Messer previews Wednesday's return, which marks the CBS procedural's 300th episode.
