S4, E15: While working on a robbery case, Kelly calls for police assistance when she observes the thieves escaping. A shootout occurs and one of the thieves, Joe Willow, escapes after killing a cop. Sgt. Cates takes his anger and frustration home where he batters his son, Greg. When Kelly realizes that Cates beats his son, she confronts the Sgt. and presses for child abuse charges. Joe Willow's underworld friends, Stone and Burke, observe the welfare court case awarding Kelly temporary custody of Greg while Cates works on the murder case. The thugs kidnap Kelly and Greg and attempt to persuade Cates to drop the search for Willow. Kelly manipulates her telephone answering service to alert the Angels and Cates to her house where she is being held captive. In the ensuing shootout, Kelly and Greg escape and the Angels apprehend the thugs and Willow. Cates admits his problem and is reunited with his son.