Danny and Aiden investigate a brutal slaughter of several employees of a fast food restaurant, which appears to have been an "inside" job. The victims were duct taped around their wrists, with plastic bags over their heads. Danny finds a heroin syringe and traces a fingerprint on it to a victim, Octavia Figueroa's, brother, who Octavia was planning to move away from. Aiden traces a fiber transferred onto the duct tape to tape used by auto mechanics, which leads to an auto body shop owned by Octavia's boyfriend and father of her kids, Luis Torres. They find a plastic bag from the role of bags used to cover the victims' heads, and they trace carpet fibers in Luis's car to the duct tape. Danny pieces the evidence together, and Luis confesses killing Octavia and the other employees because Octavia was moving to escape her drug addicted brother and taking their kids with her. Mac and Stella investigate a sawed off lower leg and meticulously track down the owner, a wannabe amputee, dead in his bed. They discover the victim tried to amputate his leg and when he wasn't successful, he paid someone to do it for him. Using crime scene photos and a print left in the victim's house, Mac and Stella track down the "hack" surgeon, an EMT, who wanted to "help" the victim and earn extra money.