Booth and Parker are playing football in the park. Booth tackles Parker and they both end up on the grass. Parker looks up and notices a bird's nest in the tree. Booth lifts up his son to see the eggs inside but instead Parker discovers a decomposed human finger.
At the lab, Cam is on the phone with Brennan. Brennan tells her that the finger did not frighten Parker. In fact, Parker wanted to keep it. Scott Starret, Brennan's newest and oldest grad assistant, isn't shocked due to his own experiences as a father.
Hodgins appears with news that sap on the finger is from a Flowering Japanese Cherry tree. Hodgins recognizes Scott. They stare at each other for a moment and Scott has it: he sold Hodgins a Vintage Hot Rod in the 1990's that broke down after a week.
Booth takes Parker to see Sweets to make sure that finding the finger didn't traumatize him. Sweets observes Parker and sees nothing wrong. He tells Booth to call if Parker exhibits signs of distress. "Like...um...killing cats?"
At the Jefferson Memorial, Brennan tries to reassure Booth. She found her next-door neighbor dead when she was five years old and she's all right. Booth isn't convinced. "You spend your life with skeletons."
Cam and Scott examine the body. "The sternal rib end indicates the victim was between 35 and 40 years old." The victim is male and has been dead for four days. There are deep puncture wounds to the trachea. The victim bled to death. Hodgins identifies pieces of freeze-dried bull penis in the fanny pack. Sweets watches Hodgins as he works and offers him an ear if he ever wants to talk. Hodgins is not interested.
Angela can only do a partial facial reconstruction because the skull was so badly damaged. Her partial matches three people in the Missing Persons Database. Scott easily rules out the first two due to height and age. That leaves Dr. Seth Elliot, a veterinarian. Scott agrees that this is the victim. Not only is he the correct age and height but "dog trainers use freeze-dried bull penises as rewards."
Brennan and Booth speak to Alice Elliot, the victim's ex-wife. He was supposed to pick up Brando, the little dog they share, but he never showed. When Alice learns Seth is dead, she breaks down. She never wanted to divorce him but Seth had a terrible gambling problem.
Karen Landrew has been Dr. Elliot's receptionist and lover for the past eight months. She is visibly upset by the news that he is dead. Booth asks about the bookie but Karen says Seth gambled online in poker games. Right after she took the job, Seth caught a man stealing Ketamine, an animal tranquilizer, from the clinic. Seth wrestled him to the ground and the thief went to prison. He was a hero.
Booth questions Tucker Payne, the man Dr. Elliot sent to prison. His dog, Schatzi, sits by his side. Booth wants to see Schatzi's teeth. They are filed to points. Having Schatzi as a weapon is not illegal. Booth tells Tucker that he is taking the dog. He hands over the paperwork. "Aw, man. You got a warrant for my dog? That's cold."
At the lab, Scott determines that Schatzi is not the killer. Scott discovered that the teeth of the killer have a distinctive crack. Schatzi is not their dog. Hodgins calls with news that Dr. Elliot's car has been found. There is dried blood inside as well as a bottle of prescription drugs labeled "Donald Timmons."
Booth and Brennan arrive at a rural property guarded by two dogs, one of them a pitbull. Booth insists they wait in the car for the owner. He tells Brennan that Parker had a nightmare about a singing frog. Brennan doesn't understand his concern but Booth is worried that Parker is acting out at school and talking back to his mom.
Someone approaches from the house. Booth and Brennan exit the car. Donald Timmons assures them that Gladys the pitbull won't hurt them. They ask about Dr. Elliot. Donald says Seth was his vet and friend from high school. He is upset to learn of his death. His son Robbie Timmons appears. Robbie worked for Seth part-time. Brennan produces the bottle of prescription pills. Robbie admits that the pills are his. His father got the prescription under his name because Robbie has no health insurance. Robbie was in Seth's car over the weekend but it was for work. On the night of Seth's murder, Robbie was with his tutor studying to get his G.E.D. His father wants him to go to medical school. Gladys warms up to Brennan. Donald shows how well trained she is. Brennan notes that Gladys' teeth are not filed.
Booth and Brennan meet with Robbie's tutor, Andrew Hopp. He is a medical student and vouches for Robbie's whereabouts, providing a complete record of their meetings. Brennan notices his suture pillow on which he practices stitching. "Next year we use actual corpses." Andrew thought Seth was a Meth addict and a poor role model for Robbie.
After getting a subpoena to download them, Angela shows Booth and Brennan photos from Dr. Elliot's PDA: they are pictures of dog fighting all taken the day of his death. In one picture, Brennan notices a blue and white ball. It's a match to the ball that Gladys the pitbull was playing with at the Timmons house.
At the FBI building, Booth barges into Sweets office, Parker in tow. Sweets is annoyed that Booth didn't make an appointment but Booth has other things on his mind. "He's having nightmares. He's not eating. He doesn't want to go to school. And suddenly, he's afraid of meteors." Sweets doesn't think anything is wrong with Parker but Booth won't listen. He steps out to get a warrant and will be back in fifteen minutes. Hopefully, that's enough time to "cure" Parker.
Cam reports that Gladys' ball was not enough to get a warrant. "Two million of them were sold last year." Hodgins mentions that he found crustaceous material in the victim's car. It is used on AstroTurf as an anti-fungal treatment. Cam's not so sure that will lead to a warrant either but Angela tells her otherwise. In one of the PDA pictures, there is Astroturf. If the anti-fungal was delivered to the Timmons house, they could get a warrant.
At the Timmons house, the FBI is ready to search for AstroTurf. Cesar Millan, the Dog Whisperer, joins them. They set off to search the premises and Brennan finds something right away: a shallow grave of dog bones, the ones who have fought to the death.
Brennan has recovered some dog skulls from the grave. Booth says they can try to track down the men who did this through their betting slips. Cesar appears: they found AstroTurf. Inside the barn, Brennan and Booth see a dog-fighting ring just like the one in the pictures. Cesar also shows them a dozen dogs chained near the ring. They all begin to bark but Cesar quickly calms and quiets them.
Booth questions Donald Timmons. He rents out the barn and had no idea it was being used for dog fighting. The tenant pays cash and they've never met. Don thought the barn was being used for storage. Don also has an alibi: he was at a seminar in Chicago during the time of the murder. There were many eyewitnesses who saw him.
At the lab, Cesar helps Brennan check the teeth of the dogs found chained in the barn. They find a match. Cesar is filled with compassion for the killer dog. Hodgins continues to berate Scott while they work together but Scott has had enough. "I didn't sell you that car. You bought it. You saw those horizontal scallops and you just had to have it. I suggested that you look under the hood but all you did was sit behind the wheel and make vroom-vroom noises." Hodgins has finally been put in his place. He apologizes and explains that losing Zach and Angela have been a lot to bear. Scott suggests he talk to someone.
Booth meets with Sweets. Parker is traumatized but not because of the finger. A girl has been bullying him on the playground. She carries him around like a monkey. Parker won't fight back because his dad told him hitting girls was wrong. He won't run away because his dad never runs away from anything. Booth is relieved and proud.
Cam, Hodgins and Scott determine that the microchip belongs to Ripley, the killer dog. The microchip leads Brennan and Booth back to Karen. Ripley's owner brought him to the veterinary clinic to be put to sleep but there was nothing wrong with him. They simply didn't want a dog that big. Instead, Seth found the dog a new home. Karen doesn't know where but she knows that he would never knowingly put a dog into a dog-fighting ring.
Brennan goes through the dog fighting photos in her office while Ripley rests on her lap. Booth is shocked to find Brennan cuddling with the killer dog. Brennan thinks Ripley is sweet. He reminds her of Booth. "He's got warm and reassuring brown eyes and he's capable of great violence." Brennan shows Booth the pictures of the dogs. Many were injured but then stitched up and sent to fight again. Brennan magnifies the image of the stitches.
Brennan, Booth and Cesar confront Andrew, Don and Robbie. They compare Andrew's suture pillow to the wound on the dogs. It's a match. Andrew has been stitching up the dogs. Ripley is owned by Andrew. Donald is only concerned about protecting his son. Robbie saw the whole thing. "Andy told Ripley to attack because he saw Dr. Elliot taking pictures of the dog fighting."
Hodgins meets with Sweets. Hodgins hates everyone. He doesn't hate everyone equally but he hates everyone: Angela, Zach, Brennan, Cam, Booth and Sweets, too. Hate is a coping technique and coping is a good thing. Hodgins hasn't isolated himself from work or friends, even if he hates them. Hodgins has a hard time believing he's fine but Sweets convinces him.
Brennan meets with Booth at the FBI. Booth tells her that Andrew ordered the dog to attack because Dr. Elliot was trying to expose the dog-fighting ring. Seth gave Ripley to the Timmons and didn't want the dog used in fights. The pictures on his PDA were evidence for the police. Dog fighting was Andrew's main source of income and without it he would have to drop out of medical school. Brennan shares her news with Booth: she is going to adopt Ripley. She bought him a leash, has set up a dog walker and a doggie day camp. She pulls out a collar that reads "Ripley Brennan." Booth has bad news: they put Ripley down. He killed someone and there was no other option. Brennan is saddened. "It wasn't Ripley's fault. People made him do what he did." She wants to know what will happen to the remains.
Brennan and Booth bury Ripley's body by a lake. Brennan covers the body while Booth tells her about Parker. "I told him to walk away if it's for himself, and to stand up and fight if it's for someone else." Brennan thinks that is a very good message. They decide to say a few words for Ripley. "It wasn't Ripley's fault that his master was cruel and selfish. Like all dogs, Ripley only saw the good in people. Dogs are like that. People should take a lesson." Brennan places Ripley's tag on his grave.