While a new rookie has joined 15 Division -- ex-soldier Nick Collins, who is trying to adapt to civilian policing after serving in Afghanistan -- the rest of the rookies are now entering their third year on the job. They have overcome the sophomore curse: that a little knowledge is a dangerous thing. However this year, the rookies of 15 Division are going to have to learn to be careful what they wish for - and they are going to learn it the hard way.