Season 4 opens with the reopening of a 1995 mall shooting spree, in which two teenagers killed and wounded several people before committing suicide. But there might be the third person involved.
I will say that, while this has a bit of that same style-over-substance thing that I hate with the "CSI" family of shows (which makes sense since this is also exec-produced by Bruckheimer), I didn't mind it as much here
