In Grand Central Station during the morning rush hour, a mother and her young daughter, Emily, are separated. Emily clutches her teddy bear as she searches for her mother, but she drops the bear when a drop of acid from a falling cup hits her on the arm. A man, acid literally melting his face and his hands screams in pain and collapses. When Mac and Hawkes arrive on the scene, Hawkes goes in the ambulance and tries to revive the man, but to no avail. Flack IDs the man as Dr. Spencer Howard, a plastic surgeon, and tells the CSIs no one remembers seeing anything helpful. Mac follows the trail of lye to where it falls off, and Hawkes borrows Emily's teddy bear, which has a footprint on it, most likely from the killer.
Stella and Danny join Detective John Scagnetti on the roof of an apartment building where the body of a young woman has been discovered. She has thin cuts and marks around her neck that indicate she was strangled, but Danny finds some GSR on her cheek. The landlord doesn't recognize her and says she didn't live in the building. In the morgue Dr. Evan Zao tells the CSIs she was definitely strangled, but the marks are too thin for rope. Zao also tells them the dead woman was blind.
Flack pays Howard's medical partner, Dr. Stanley Thatcher, a visit to ask if Howard has any enemies, but he brushes the detective off, saying that plastic surgery is a delicate business and there are always dissatisfied customers. Back in the lab, Hawkes lifts the footprint pattern from the teddy bear and determines it's a left footprint, and that the killer walks on the balls of his or her feet. Across the lab, Danny determines the substance he discovered on the blind woman's cheek wasn't GSR but carbon steel subjected to high temperatures. Scagnetti brings the CSIs the woman's purse, and an ID: Evelyn Danner. A visit to her apartment reveals that she was a sculptor of human busts. Stella becomes curious about an unfinished bust, while Danny finds a letter written in Braille.
Back at the CSI labs, Aiden tells Mac she has nothing on the Regina Bowen rape case and he orders her to keep searching until she finds something. In the morgue, Dr. Zao shows Mac and Hawkes that Howard inhaled lye and also had a brown substance on the sleeve of his coat, which Zao sent to the trace lab for analysis. Mac puzzles over a burn mark on the top of the man's hand, but and a trip to the dummy lab proves that the mark could only be made by a direct pour onto the hand, but Mac notes that it's evidence without context for now.
Danny decodes Evelyn's GPS navigator, which leads the CSIs to the place she was the night before the murder: a cuddle party. Stella and Danny look on in amazement as adults clad in underwear and sleepwear rub up against each other. The "cuddle caddy" who watches over the party recalls Evelyn and remembers she frequently cuddled with an amateur hockey player whose name he can't recall. Stella calls in a sculptor friend of her, Frankie Mala, to finish Evelyn's sculpture, and a Braille expert reads the letter to the CSIs: it's from Evelyn's ex-boyfriend, Steve, asking her to get back together with him.
Mac is finally able to locate the cup that served as the container for the lye when he questions the sax player at Grand Central. He takes it to the lab where he uncovers a logo on it--Zelco. Stella and Danny track down Steve Sampras, Evelyn's ex, who is with his hockey buddies. Steve also lives in the building where Evelyn's body was found. Steve denies killing Evelyn--they were getting back together, he tells the CSIs, so he had no motive. Danny takes Steve's skates and those of the entire team for analysis in the lab.
Back at the lab, Mac goes over the evidence from both of Regina Bowen's rapes and discovers an empty evidence packet with the tape cut open. When Stella stops by his office, he shows her that Aiden has tampered with the evidence from the case. Elsewhere in the lab, Flack tells Hawkes that Howard had three lawsuits pending against him. Lab tech Zack Shannon tells them that Howard had painkillers in his system and that the brown substance on his sleeve was tanning lotion. Flack questions the three people bringing complaints against Howard, but none of them seem to be his killer.
Danny examines all the skates while Zack runs the dust from the blades. Frankie has completed the bust Evelyn was working on, revealing Paul Deacon, one of Steve Sampras's hockey friends and his roommate. The metal shavings from his skate match the ones found on Evelyn's face. Hawkes is catching a quick break for takeout and watching a Jennifer Lopez video when Mac stops by with another lead: the logo on the cup was from a pharmaceutical company that sent them out to various doctors, including Howard's office. As Hawkes watches J. Lo's video, another piece of the puzzle falls into place.
Danny and Stella head back to the roof of the building where Evelyn was killed where they discover the murder weapon--a ribbon--tied around one of the trees on the roof. Back at the CSI offices, Hawkes shares his revelation with Mac: Jennifer Lopez insured her butt because of its importance to her image, and Dr. Howard had his hands insured in a similar manner, to the tune of ten million dollars. The CSIs realize that the murder they're looking at is actually an insurance scam gone wrong. The doctors and nurses from Howard's practice are brought in and footprinted. Howard's partner, Stanley Thatcher, turns out to be the match.
Stella and Danny confront Paul, who heard a make up message Evelyn left for Steve on their answering machine. Evelyn came over to see Steve, but found Paul instead. He brought her to the roof and angrily asked her why she was dumping him. She retorted that Steve never saw her as just a blind girl and, in a rage, Paul killed her. Stella cuffs him, noting that Evelyn was able to see right through him.
Mac presents his evidence to Thatcher: the lawsuits against Howard were dragging the practice down, so Thatcher concocted a plan to pay the bills and end the partnership with Howard. Thatcher would pour lye on Howard's hands at rush hour in Grand Central, where plenty of people would be around but no one would notice. But when someone knocked into his arm, the lye flew out of the cup and into Howard's face. Thatcher fled. Mac marvels at the stupidity of the plan.
As Hawkes sews up Emily's teddy bear and prepares to mail it off to her, Mac handles a less pleasant task. He calls Aiden into his office and shows her the empty evidence bag, asking her what she was thinking. Aiden says she didn't plant the evidence, though she admits she wanted to. Citing his need to protect the integrity of the lab, Mac fires her. She puts her badge on his desk, saying she can't do the job anymore and that she wouldn't trust herself next time. She asks him to catch Regina's rapist before walking out of the office for the last time. Stella checks on Mac, who stands pensively by the window.
Scott has no lines in CSI NY: Murder at Grand Central Station.
Some Information courtesy of The Internet Movie Database