Mac walks across a vacant lot. He descends into a hole to catch up to Hawkes, who is photographing the body and scene. Don identifies the victim as Kevin McBride. He says some BMXers were doing trick on the lot, when one of them fell into the hole, and found the body. Mac and Hawkes note that the victim's core body temp of 55 degrees (Fahrenheit), makes the time of death about 36 hours earlier, around 9-10 AM, the day before. Skull fractures and marks on the face indicate strong blunt force trauma. Mac follows a trail of blood up the steps. It ends at the top step. The perp must have dragged the body down from the surface.
Stella is at another scene, where she has found a cleaned up blood trail that goes to a doorway, and stops. When he asks where she is, she says she's in the middle of the East River. She's in a house, on a barge, traveling in the river.
Danny shows up at the moving house barge, in a speed boat. He tells Stella and Lindsay that McBride owned a house relocation company. His latest job was moving this house from Staten Island to the upper east side for stockbroker Franco Vladek. Vladek has been in Beijing for the past six months. The three discuss the scenario. A broken window with no glass on the floor indicates that maybe the killer broke in after the house was secured, killed McBride, and cleaned up the mess. Why, though, would McBride have been in the locked up house?
After Sid's autopsy, McBride's wife, Annie, and daughter, Ella, come to identify the body. The daughter tells Mac that her father had a distinctive scar on his left index finger. The mark on his hand, she says, was from an accident while slicing a bagel.
Back in the house, Stella finds a recently-fired shell casing. Since Kevin McBride wasn't shot, Danny asks if they should be looking for a second victim.
After Detective Angell talks to McBride's secretary, Don comes over. She tells Don that she saw his sister at a party where they were responding to a call. She adds that they didn't take her in, because she mentioned his name.
Danny tells Lindsay that Angell found nothing in a background check on the moving crew. She shows him a piece of cardstock that Sid had removed from McBride's hand. The fragment shows an eyecthat matches the victim's eyecand the word "tell" scrawled on it.
Stella receives a call from a blocked number, "The fisherman's death is an unsolved case." "Be smart about this, Detective. Don't try to be the hero."
Lindsay finds part of a QR (Quick Reference) code on the back of the card. She shows Stella and Danny how QR codescessentially a two-dimensional barcodecis encoded text that can be read by a camera phone, and converted to a website, or other information. [They're very popular in East Asia, but are still slowly catching on in the U.S.] She runs off to try to decipher the code.
Stella reminds Danny of the Rat Fisherman. She tells about the man from the embassy who spoke fluent Greek, and must be the man who attacked her, a few weeks before. He must also be the one who killed the Rat Risherman, and the phone call was a threat.
Hawkes tells Sid that a hair found in the victim's nose matches that of the Virginia opossum. Sid shows him lacerations on the wrist that appear to have happened right before death. The opossum ate bits of McBride's face, taking away potential soft tissue evidence of the murder weapon. Hawkes, though, finds a pattern in the bone fragments from McBride's skull.
Stella walks in to find Adam smoking from a gourd. He tells her that the carrot from the scene was a "veggie pipe", hollowed out and showing traces of THC. Stella notes that tests on McBride didn't indicate any controlled substances, so it might be the killer's. Adam adds that he has DNA from the carrot.
Don confronts his sister at a bar. She deflects his concern with a childhood story. She promises not to use his name to keep out of jail.
Stella visits the shop of Tanner Somerset, and flashes her badge. He sits up and tells her the paraphernalia in his shop are for legal use onlyca sentence which she helps him finish. She tells him that his DNA was found on the carrot pipe found at a murder scene. He tells her that the house looked like a good place to light one up. So, he broke in, smoked, and fell asleep. He woke up the next morning, and the house was moving. So, he rushed out.
Danny matches the marks on McBride's skull to a framing hammer. The marks also match those found on nails at the crime scene. Problem is that it's a common tool, available anywhere. Hawkes tells him that the scale that Sid removed from the victim is from a gara rufa fish, a carp native only to Turkey, Syria, and Iran.
McBride's daughter complains to Mac about their taking all of her father's things. She pleads with him, because her mother is very upset. He tells her that they'll find the person who killed her father.
Flack gives Danny a framing hammer found in a dumpster a couple blocks from the crime scene. He also found out that numerous people had reported seeing a man jump from a moving house, corroborating Somerset's story. When he and Danny come upon Lindsay fretting over the QR code fragment, he says he recognizes the card and the border around it.
He and Lindsay head over to the bar where Flack's sister works. She finds the cards, but the manager tells him that his sister had been fired two weeks earlier. She shows up and tells Don that she's there because she works there. He replies that he knows she was fired. She dismissed it as no big deal. He wants to know why she is drinking and hanging out with a no-good crowd. She asks when he started caring.
Hawkes demonstrates to Stella how a tank full of gara rufa fish are used in manicures. For $50, you can stick your hands in the tank to have the fish eat dead skin for thirty minutes. Stella tells him that Rita, McBride's secretary, told her that she had a manicure the morning of his death, around 10. The long, deep, scratch marks on McBride's arm, where Sid found gara rufa tissue, could be nail scratches. Danny walks in with news that Tanner Somerset had lived in that house. His mother sold it out from under him six months before.
Rita tells Danny that she had fallen, and McBride caught her. That's when she accidentally scratched his arm that morning. Stella confronts Somerset with a receipt for a framing hammer that he'd just bought. He says that he was mad that his mom kicked him out and sold the house. He was angry and went over to mess up the house. She notes that the only thing messed up was McBride. He denies seeing McBride, while he was in the house.
Lindsay shows Mac that the cards are for a website: Secrets You. People in bars fill out their secrets, get a PO Box address from the QR code, and the site owners post them on the website. The PO Box, however, is paid for in cash, so the owner is unknown.
Hawkes comes in with news that blood on the handle of the found framing hammer match McBride. The handle has epithelials, but they are female. They're too degraded, though, to match definitively. Adam bursts in, and reports that the cardstock had compounds commonly used in organic floor stains. Feathering on the edge of the card where he found the substance indicate directionality, and that it was dragged along the floor, after it was torn. Mac asserts that the other card fragment must still be in the house.
Using a heat gun, Mac dries the bottom of the flooring in the house. A piece of cardstock peaks out from between the floorboards. The whole message on the card was, "I'll tell her, if you don't."
Lindsay finds several instant message streams in deleted files from McBride's computer. For the past two months, though, all of the messages are between McBride and a "Lola57. He had emailed a photo to Lola57 the week before his death. It matches the photo on the postcard. She stopped all communication after that. He tried to contact her, but she didn't respond.
Don goes to his sister's apartment. She's been drinking and doesn't want to talk. He apologizes, then pulls out his phone, and plays the Peter Gabriel song Red Rain over the intercom. She's moved.
Hawkes shows Mac a video walk-through of the house, that Annie McBride made the morning of Kevin's death. Lindsay comes in with the identity of Lola57.
Mac shows up at the apparent home of the confessions website. Ella McBride. Mac tells her that he knows that she tricked her father. She confesses that she was Lola57, but it wasn't a trap. A couple months earlier, she met someone wonderful online. Mac realizes that she didn't know about her father's activity, until she received his photo. She sent the postcard to get him to stop, but swears that she didn't kill him.
Stella tells Mac that mitochondrial DNA from the hammer matches Ella. Since mitochondrial DNA is an almost perfect match between a mother and her children, it could be either of them. Annie told them that she was in Montauk, making the walk-through video. Ella claims she was gluing up Secrets You cards in her loft.
Stella watches Annie's video. She calls in Annie McBride. A shadow of someone outside the house, indicate that it was 2 in the afternoon, not 10 in the morning. So, she changed the timecode to set up her alibi. Annie tells her that she found the postcard, and realized that he was cheating online.
Outside the interrogation room, Ella asks Mac if her mom knows about Lola57. He tells her none of it was her fault. She says that the man she met online was so understanding, and made her feel important. He was nothing like her father.
Don follows Samantha. She goes to an alcoholics' support group, where he hears her confessing that her last drink was only 20 minutes ago. He meets Jessica outside, and tells her that he didn't need a ride. He says his family is stubborn, but they're going to be okay.
Back in the lab, Stella opens a package, and is startled by the contents. She shows Danny the dead rat inside. She says that, concerning his question the other day about wanting to break some rules, "I do now."