Mac comes within an eyelash of getting killed (a gun in his face with the man pulling the trigger but the gun not going off). After that horrific experience, a shaken Mac then - perhaps with retirement in mind - attempts to get closure in his job by re-opening the last unsolved crime that's still on his desk.

He goes back to a killing at a bodega from nine years ago and, this time, discovers a clue indicating that in addition to the double homicide, they also was a little girl kidnapped at the scene! More than finding the killers, he's interested in getting back the kidnapped child. How he and the CSI gang goes about it is interesting and fills the second half of the crime story. I especially enjoyed the performances of Clayne Crawford ("Wes") and Kayla Carlson ("Olivia").

Meanwhile, Danny finds out he has passed the Sergeant's test will be "Sgt. Messer." Does that mean he's gone from CSI?

In the end, a totally stressed-out Mac silently leaves the CSI building and walks alone down the streets. The question is: is this end for him? Has this job gotten to be too much?