Mac and his team investigate the murder of a missing wife, LeAnn Goodman, whose body turns up on a Brooklyn Heights hillside. Dr. Hawkes' autopsy reveals LeAnn suffered a hemorrhagic stroke, perimortem smoke inhalation and bedsores. Danny discovers LeAnn inhaled "fry sticks", a cigarette laced with cough syrup. Mac finds a second victim, Russian student Zoya Pavlova, on a garbage barge with similar neck contusions and lividity marks, and determines they're looking for a serial killer. Autopsy reveals the killer broke Zoya's neck. A camera recovered on the garbage barge, gives Mac and Stella a picture of Zoya in front of an unknown brownstone, and they use reference points in the picture to triangulate her location. At the brownstone, a third victim is found hooked to a respirator barely alive. Mac and Dr. Giles determine the killer strategically strangled the victims in an attempt to "lock" them into their bodies, brain activity with complete paralysis, and didn't perfect the maneuver until the third victim. The "Jane Doe" is paralyzed but communicates with Mac by blinking, answering a few questions before suffering a stroke that leaves her in a coma. The brownstone and medical equipment are void of fingerprints but a medical bag with the initials "B" and "I" in Cyrillic lettering lead Mac to Zoya's sponsor Dr. Bogdhan Ivanov. DNA on the bed sheets matched to Bogdhan and Zoya, and he confesses to making love to her. Bogdhan "loved" Zoya and when she wanted him to take care of her, he decided to "free" her from the burden of daily life. However, he accidentally broke her neck in the paralyzing process and found two other similar looking victims on which to perfect his process. Mac visits the comatose "Jane Doe" and tells her about his wife Claire who died unexpectedly and a single tear rolls down her check. Mac pays a visit to a place that reminds him of Claire.