On the border between Texas and Oklahoma, BOOTH and BRENNAN meet with a TEXAS RANGER and an OKLAHOMA SHERIFF. The bickering cops are in the middle of a jurisdictional dispute. They show Brennan to a set of remains. The harsh, dry climate has obliterated everything but the bones. Brennan determines there are two females in the shallow grave. "A lesbian suicide pact," suggests the Texas Ranger. Brennan disagrees. These females were not lovers: they were conjoined twin sisters.
At the lab, Brennan examines the bones with CAM and VINCENT NIGEL-MURRAY. "Conjoined twin births occur once every 85,000 births," Vincent notes. ANGELA joins the group with news that a sandstorm eight days ago unearthed the remains. Brennan and Vincent agree that the victims were between 19 and 21 years old. Angela believes they will be easy to identify. "How many sets of conjoined twins can there be?" She sets off to conduct a search. HODGINS enters with a theory. In the soil beneath the victims, he found popcorn and mites from hundreds of miles away. Could the girls be from a traveling circus? Angela returns, her search a success. The victims are JENNY and JULIE VAN OWEN, juggling Siamese twins.
Booth and Brennan consult with SWEETS in his office. Sweets doesn't believe an investigation at the circus will produce results. "Circus folk are extremely tight-lipped and close-knit. They won't tell you anything." Sweets knows firsthand. He was adopted and when he tried to find his birth mother, a circus psychic, no one would give him any information. Brennan agrees. "I studied a carnival for six weeks as research for my cultural anthropology dissertation and they wouldn't tell me anything. Even though I became quite adept at the high wire." She and Booth come up with a plan: they must join the circus.
Before they become circus folk, Booth and Brennan speak to SANDRA HICKS, the mother of the twins. Sandra blames the circus for stealing her daughters. She has plans to sue them, with the help of her lawyer and husband DELL HICKS. Sandra last saw Jenny and Julie four months ago. Jenny told her to stay away and Julie didn't argue with her overbearing sister. Brennan asks about surgical separation. Jenny and their doctor, DR. MUIR, believed separation was possible. Julie and Sandra thought the procedure was too dangerous.
At the doctor's office, Dr. Muir explains that even though he thought Jenny and Julie could have been separated, it didn't matter. The twins had to make the decision. Brennan is curious if the twins thought being separated might hurt their circus career. Dr. Muir isn't sure, but he does know that the girls loved the circus and had big plans for their act. Booth asks Dr. Muir to send their file to the FBI. They have another appointment.
A trailer emblazoned with Booth and Brennan's faces pulls up to Bingham's Circus of Wonders, currently located in Texas. The trailer reads Buck and Wanda Moosejaw's Knives of Death. Booth and Brennan (as Buck and Wanda) speak with HENRY SIMON, the owner and ringleader. He agrees to let Brennan and Booth perform. They'll do the first show for free. If Henry likes it, then they'll talk payment. Booth gives Henry a little taste. He throws three knives into a wooden post. Brennan is impressed. Booth wasn't lying about having the best knife-throwing skills in the Rangers. Henry calls LAVALLE, a little person, to show Booth and Brennan where to set up.
Back in their trailer, Booth immediately calls Sweets. Sweets offers to send the pair a lexicon so they can learn the circus lingo. Sweets also gives them some advice. "Act like you're more interested in each other than any of them; they will come to you." Later, Booth and Brennan rock their trailer so that Henry and Lavalle think they are more interested in each other. "Let's just hope they're as good outside the trailer as they are in," remarks Henry.
Booth approaches Henry and Lavalle inside the Big Top Tent. He asks about Jenny and Julie. "We worked a carnie up in Alaska last year. Nice kids. Said they were coming down here to work at Bingham's." Henry and Lavalle report that the twins left the circus. Brennan approaches just as Henry pulls out a note from Jenny and Julie. The girls write that though they love the circus, they have to move on. Henry and Lavalle walk off, allowing Brennan to pocket the note.
At the lab, Cam and Vincent watch a video of Jenny and Julie during their juggling act. Hodgins reports that there were chalk particulates on both bodies. Angela has more news. Brennan sent her a picture of Jenny and Julie's note. According to Vincent, Jenny was the left-handed twin, yet on the note, Jenny signed her name with her right hand. The note is a fake.
In the Mess Tent, Brennan and Booth have their first circus meal. Booth scoffs at the clowns as he passes by and sits with Henry, Lavalle, MADAME NINA and MAGNUM THE STRONGMAN. Luckily for Buck and Wanda, talk turns to Jenny and Julie. Everyone at the table misses them, but they mention that the clowns were not fond of the girls. Jenny and Julie borrowed their equipment without asking so they could expand their act. Madame Nina mentions that Julie had a boyfriend: an outsider boyfriend.
Booth and Brennan sit in their trailer. They speak to Hodgins and Cam via laptop. Hodgins can't believe one of the girls had a boyfriend. He wonders how that might work. Cam wonders if there is only one bed in Wanda and Buck's tiny trailer. Brennan gets them back on track. "Ask yourself if you found anything that suggested a relationship." Hodgins found hair gel under Julie's fingernails. Julie must have run her fingers through someone's hair. Hodgins mentions that the gel would smell like sandalwood. Booth immediately knows the brand: Smoothsure Power Hold. Dr. Muir was wearing a ton of it.
Booth and Brennan borrow a motorcycle and sidecar so they can question Dr. Muir. Meanwhile, at the lab, Vincent discovers matching fractures on both Jenny and Julie's skulls. They are sometimes known as kissing fractures.
At Dr. Muir's office, Dr. Muir admits to a relationship with Julie. He dated Jenny first, but then fell in love with her sister. Jenny wasn't happy about it. Sandra Hicks wouldn't have been happy about it either, so the relationship was a secret. Dr. Muir tries to explain himself. "A fair amount of privacy could be achieved by an eye mask and an MP3 player turned up very loud." Booth doesn't need to hear anymore. He arrests the doctor on suspicion of murder. The other stuff may not be illegal, but it sure is troubling.
On the way back to the circus, Brennan is eager to discuss their act. They have to perform that night. Booth sees no need to go on with the show. They caught the culprit. Booth's phone rings and Brennan answers it. Dr. Muir has been cleared of all charges. The show will go on.
At the lab, Angela runs scenarios with Vincent and Cam, who is starting to find Vincent's trivia less and less endearing. Vincent rules out whiplash and a hard fall while Angela rules out a separate attack with the same weapon. Their heads could have been conked together by a weapon, but there was no evidence that a weapon was used. Perhaps the weapon was soft, like a clown's prop? Cam will tell Booth and Brennan to look for possible murder weapons.
At the circus, Booth and Brennan ready for their act. Booth is clad in a long coat and fake mustache while Brennan dons a Princess Leia inspired hairdo, sequined outfit and gold cape. Booth is taken aback by how beautiful she is. Brennan and Booth proceed to look through the clown's props for a possible murder weapon but the clowns catch them. Brennan pretends they were simply looking for a prop for their act. The clowns are not appeased. They don't want anyone going through their things. Henry steps in and breaks up the fight, so Tumbles and his clown posse retreat. Booth also turns to leave but he accidentally knocks Brennan in the eye with a huge fake hammer. Brennan is injured but she won't retreat from the performance.
Brennan and Booth parade around the circus ring with the other performers as the show begins. Brennan, who now sports an eye patch, is getting very into character. Backstage, Brennan gathers props for their act. Booth is not interested in any of Brennan's flair. He just wants to get through this without killing her. Suddenly, Lavalle is at their side. It's time.
Booth and Brennan emerge from behind the curtain and the audience applauds. A webcam allows Sweets, Cam, Angela, Hodgins and Vincent to watch from the lab. Booth seems nervous but Brennan is ready and willing. She stands in front of a board surrounded by balloons. Booth places her in the middle and steps to his mark. He hesitates before throwing the first knife but POP! He successfully breaks the balloon. Booth gains more confidence with every throw. Soon, all the balloons around Brennan have been popped. The crowd goes wild. Booth is relieved that it's all over but Brennan has other plans. She pulls a foam apple out of her bag, puts it on her head and stands against the board. Booth has no choice. He throws one of his knives. It hits the apple. The crowd is amazed. Booth and Brennan take a bow. Then Brennan pulls a clown nose out of her bag. Booth is shocked. Brennan dons the nose and steps up to the board. The crowd cheers for Booth and the drum roll begins. The knife sails through the air and pierces the nose. Brennan is unharmed. Even Henry and Lavalle are impressed.
Backstage, Brennan and Booth are quite pleased with one another. After congratulating themselves, they look out to see the next act. Magnum wields a mallet. He hits a seesaw and sends an acrobat flying into the air. Brennan believes he has the necessary force to assault the twins with a soft, foam weapon and cause fatal damage.
After the show, Booth and Brennan confront Magnum about Julie and Jenny. "They're dead, but you knew that, didn't you?" Magnum literally breaks the nearest wooden beam in two, releasing a net onto Brennan and Booth. He takes off running, leaving Brennan and Booth struggling to free themselves.
Booth puts out a BOLO on Magnum while Brennan gets a report from Vincent. He found fractures on Jenny and Julie's lower legs and feet. Brennan becomes animated when she hears how much Cam and Vincent liked their routine. She has more ideas for the act, but Booth tells her it's over. They have to question the other performers.
In the ring, Henry demands an explanation about the scuffle with Magnum. Brennan tells the truth: they were questioning him about Jenny and Julie's death. Booth pulls his FBI badge and the room begins to clear out. The circus performers won't talk to the FBI. It looks like the case has hit a dead end. Brennan decides this is her shot to try the high wire again. She runs to the ladder. Booth tries to talk her down. It's no use. He closes his eyes. Brennan seems to be doing well on the wire, but she soon realizes she isn't in shape for this. The bones in her feet begin to hurt and she falls into the net below.
Brennan is unscathed. She has a realization. The twins had fractures on their feet because they tried to walk on the high wire. When they fell, their heads knocked together, killing them. Magnum returns to defend himself. He would never hurt the twins. Booth and Brennan believe him. The circus didn't call the authorities about the accident because Jenny and Julie's mother would have sued. If that happened, the circus would have had to close its doors. Magnum buried the girls so Booth arrests him for interference with a dead body. Brennan promises to get Magnum a good lawyer. All the circus performers gather around him to say goodbye.
In the morning, Brennan and Booth emerge from their trailer to find everything gone. The circus packed up during the night and left. Brennan and Booth reminisce about their time as performers. Booth finds a flyer on the ground that lists Buck and Wanda's act. Neither of them wants to leave.