Where We Left Off: After a near-death experience and drama with his old partner, Mac told new co-worker Jo that he was satisfied with the amount of good work he'd done, and walked off into the sunset. Then, the show was renewed for another season, so ...

What's Next: The season premiere will find Mac dealing with the 10th anniversary of the death of his wife (Jaime Ray Newman) on 9/11. Also, 'Breaking Bad' star Dean Norris guests in an October episode, playing an Internal Affairs detective who investigates a shooting that involves one of the 'CSI' gang, and 'True Blood' and 'Dexter' alum Courtney Ford guest stars as a car thief in a fall episode.

Season 8 premieres Fri., Sept. 23, 9PM ET on CBS