A Dispatch call hones in the CSIs and NYPD to a rough neighborhood of Bronx where reports say that there is domestic violence in progress. The roar of a woman's scream alerted the neighborhood in this peaceful Saturday afternoon.
It doesn't take long for the responding officers to arrive on the scene en-masse. Mac Taylor and Danny Messer are quick on the scene. Guns drawn, Mac and Danny along with a flag of officers file into the eerie and dark residence if the McCartny family, looking in vain for any sign of life in the premises. The atmosphere the cops breathe in from the house, one could tell Death was just here. As they make it to the master bedroom, a horrific scene stands in the form of Lily McCartny, mouth duct-taped, bound on a chair, beaten to death. And lying next to her dead body is her husband, Dan McCartny, throat slashed, blood splayed everywhere. A bloody baseball bat in his hand piques Mac's attention.
Danny and Flack continue to search the house. When they check the kitchen, they hear a ruckus; tag it along with gravitational blood drops leading towards the kitchen sink. Danny has summoned enough courage to open the sink cabinet expecting to see the killer. But instead, it's Lester McCartny, the 13 year old son, badly bruised and bleeding profusely from a cut to his thigh, his mouth covered by his bloody hands, trying to quell the fear and pain away. Danny reaches out to the boy who he escorts out of the house. When Lester sees his dead parents, he panics as fear overcomes him for the killer might strike back at him, and goes limp in Danny's arms. Danny swears he would protect him. He coaxes Lester out of this horrible tragedy, shielding him from seeing again his slain parents. With that, Danny has earned Lester's trust.
Day turns into night as Mac and Stella continues to work the scene with Peyton. Flashlights illuminates the dim lighted home of a once lovely family.
As Danny takes the scene, he is called back by the attending EMT who cares for Lester. Lester refuses to be treated not unless Danny is there. The boy trusts Danny and only Danny. When Danny arrives, a smile is evident on the boy's face. Danny confides to Lester that it's okay. The boy shakily opens up his arms only to reveal a lacerated wound pertuding across the palms. Danny is genuinely shocked by the wounds this boy has received from a bad beating. "What did this family do wrong to someone do something violent as this?" Danny wonders.
Summary: A grizzly murder of a what seems to be a normal,happy family catches Danny off guard while the CSI team try catch a murderous "Evil Twin" killing duo.