Deep in the woods, a young couple disrobes and hops into a hotspring. As things begin to heat up, the girl pulls from the bubbling mud a muddy skeletal hand.
Booth and Brennan are now on scene with the park ranger. It's possible the body was cooked in the mud. But the blunt force trauma on the skull tells Brennan boiling wasn't the cause of death. She wants all the mud brought back to the Jeffersonian for further exploration.
In the lab, Zack tells Cam the victim was hit in the head with some sort of square pipe. But damage to the face suggests another weapon. It's possible there is more than one killer.
In Dr. Sweets' office, Booth and Brennan discuss the case. Sweets picks up on the partners inability to discuss their personal lives with each other. All the two ever talk about is work. The doctor prescribes an evening out with him and his girlfriend to discuss anything but work, a double-date. Booth and Brennan reluctantly agree to it.
Hodgins and Zack are sifting through the mud when Cam enters with the news of the body having been in there any where from ten days to two weeks. Zack and Cam discuss the numerous broken bones on the victim.
Brennan is on the phone with Sweets setting up the double date as the two partners walk to Booth's office. Booth is weirded out by the situation, especially after learning the date will take place at a ceramic class. Angela gets a hold of them through the computer. She has the facial rendering of the victim and Booth quickly recognizes him as Tripp Goddard, the motorcycle racer. He won a huge race two weeks ago.
Booth and Brennan arrive at the Slam Bolt Garage. They meet with Philippa Fitz, a female racer and Garth Jodrey, a racing journalist. Tripp raced for Philippa's family team, Slam Bolt Racing. Garth mentions how the fans loved Tripp, everybody else hated him though. Before he can elaborate, Philippa's father Lenny enters and shoo's Garth away. Lenny says Garth is just angry with Tripp for putting him in a wheelchair. The Fitzs last saw Tripp leaving his victory party two weeks ago. They are in full cooperation with the investigation and just want the killer caught.
In the FBI conference room, Booth, Brennan, and Garth watch footage of Tripp gloating after winning a race. On screen, Danny Fitz, Philippa's twin brother, is visibly angry with Tripp. It looks as if Tripp clipped Danny to win, even though they're on the same team. It's the same move Tripp once did to Garth, the move that put him in a wheelchair. Garth says Danny and Tripp left the party around the same time that night. Garth left shortly after, but that's all he's saying without his lawyer present.
Zack enters the lab with a bunch of metal pipes and crow bars. He's looking for the murder weapon. But Hodgins found particulates in the skull that point towards something else: handmade motorcycles. Through some deductive reasoning, the two of them are able to narrow the weapons down. From the pile, they decide on a narrow steel bar.
In the FBI conference room, Booth and Brennan sit with Danny Fitz and his lawyer, Braxton Smalls. Danny admits to beating up Tripp a few years ago, after he found Tripp cheating on Philippa. Danny isn't frightened by Booth and his tactics, but he's intrigued by Bones and doesn't hesitate asking her out. Booth quickly makes her mind up for her: she will not be going out with a murder suspect.
Hodgins and Zack report their findings to Cam and Angela. A weapon like the cross-section bar they've decided on matches the type of weapon used on the back of Tripp's head. But they have nothing on the frontal skull injury. And the amount of force used to bash in Tripp's skull doesn't eliminate anybody from the suspects list, it wouldn't have taken much.
Back at the motorcycle garage, Booth talks with Hodgins over the phone. Hodgins has identified a clear liquid on Tripp's body. It's called Toluene and it's used to clean up oil. And as Booth hangs up with Hodgins, Brennan makes her way over to a shelf full of the stuff. Apparently toluene is good for cleaning blood, as well. An FBI tech trains his ALS light on the drain and it glows: positive for blood.
The partners are in Sweets office where the work-related discussion continues. Booth is worried about going on the "date" and going to a ceramics class, where he'll be forced to make something. But it's too late; he's already agreed to it.
Booth and Brennan are at the motorcycle track where Danny is ready to take out Tripp's bike, seeing how he's now number one on the Slam Bolt racing team. He's got nothing to say without his lawyer and he takes off on the bike. Booth, Brennan, and Lenny watch as Danny races around the track and lose control, crashing and igniting a fireball that engulfs the racer.
Booth and Brennan are now in the garage where a FBI Motor Tech looks over the charred motorcycle. She is able to quickly determine the bike was tampered with, meaning somebody murdered Danny. Somebody that was familiar with bikes.
In the lab, Hodgins and Zack are able to recover partial lettering off a plastic pen found in the mud pit. It's a pen from the website Garth writes for and it's possible the pen fell into the mud when the body was being dumped.
Booth, Brennan, Sweets and his girlfriend, April, are in a ceramics class working with clay. Booth mentions how he thinks a paraplegic man killed Tripp. The work-related conversation is quickly redirected into a debate about fish and whether or not they have souls. When Sweets tries to correct April, Booth and Brennan find themselves in the middle of a lovers spat. A clay fight helps to lighten the mood.
In Booth's car, the partners get a call from Zack and Hodgins. They're still working on the weapon but know its some form of pry bar. Hodgins has also discovered a small shard of glass on the victim's forehead. The film coating on the glass suggests a mirror.
Booth and Brennan arrive in a desert clearing where Tripp's stripped truck has been discovered. In the bed they find a pry bar just like the one Zack and Hodgins have been searching for. The driver side mirror is cracked. Tripp must have been hit over the back of the head with the bar, smacking his head into the mirror with the impact. The FBI tech opens the trucks storage box to reveal the inside lined with dried blood. They've also found some hair in the box. Short and dyed, but gray at the root. It points to Lenny Fitz.
Booth and Brennan are in the interrogation room with lawyer, Braxton Smalls, and his new client, Lenny Fitz. Lenny claims the forensic evidence they've got on him is tied to a hug he and Tripp shared before Tripp left the victory party. Lenny also tells them about his decision to give Tripp part of his Slam Bolt energy drink company. In exchange, Tripp was to race exclusively for the company. But the contract never got signed. Tripp died the same night he received it and its whereabouts are nowhere to be found. Lenny had good reason to keep Tripp alive.
Booth and Brennan are back in Booth's car. Brennan thinks Danny and Philippa conspired against Tripp when learning of their father's decision to the younger racer ten percent of the company. But Booth's not so sure. He wonders who else knew about the mud pit.
Booth has Tim, the guy who discovered Tripp's body, in his office. Tim gives up Garth as the one who told him about the mud.
In the lab, Brennan, Zack, Hodgins, and Angela look over the murder weapon. By determining where the blood splattering started on the pry bar, the team is able to gather the murderer was choking up to be able to swing the weapon, not having been strong enough to swing the whole length of the bar.
April shows up in Brennan's office. She wants to know what Brennan thought of her and Sweets together: if they seemed good together. April thinks Sweets is losing interest. Cam enters with the DNA results off the weapon. The killer is a female.
Booth and Brennan are, again, in the interrogation room with Braxton Smalls and his newest client, Philippa Fitz. After a bit of fighting from Braxton, Philippa breaks down and admits to killing her brother after he mistakenly rode the bike she had rigged for Tripp. When Tripp didn't ride it for a while she took the pry bar over his head and threw him in the mud pit. Braxson knows there isn't enough evidence to convict his client but Booth's going to make the arrest anyway. It's important everyone know what Philippa did.
In the conference area of the lab, Booth and Brennan discuss the case. Sweets enters having just been dumped by April. And Booth and Brennan invite the heartbroken doctor to go bowling with them.