Sipowicz endures every parent's nightmare as young Theo's visit to the doctor reveals a problem; the subject of Kirkendall's ex-husband strains Jill and Diane's partnership, but they work together to solve the brutal murder of a rapist. Danny and Andy consider some horrible options related to Don's return and Jill's actions regarding her ex. A father and son don't have wonderful motives for taking revenge on someone who wronged a family member.