At the lab, Clark Edison, works through lunch to catalogue unidentified remains before Brennan's return from London. Angela insists he come to lunch. The divorce papers are signed and it's time to celebrate. Birimbau arrives to say goodbye and Cam offers to drive him to the airport. His flight is cancelled. Fortunately, Cam is there to keep him company. They sleep together in his hotel room.
In London, Brennan and Booth are ready to leave. Brennan wonders why Ian Wexler, an English colleague, hasn't called. Booth is convinced Wexler is a jerk. He won't see Brennan off because she refused to sleep with him. Booth decides he wants to be a knight: Sir Seeley Booth. "It just sounds right." His phone rings as Brennan rants about meaningless titles. Booth's face drops. Something has happened to Wexler.
At the lab, Angela and Hodgins attempt to help Clark catalogue remains but all they can talk about is their wedding, much to his annoyance.
In London, Inspector Cate Pritchard waits for Booth and Brennan outside Wexler's flat. She asks for their help. They may have found Wexler's body. There is a charred skeleton on the bed. It appears as if Wexler put a kettle on the stove but there was a gas leak. He lit a cigarette and his flat went up in flames. However, Wexler didn't smoke and there is no water in the kettle. Cate doesn't suspect murder. She just needs Brennan to identify the victim. Brennan looks closely at the bones. There is trauma to the frontal bone that occurred before the fire. This is a murder.
At the lab, Sweets meets Cam at her request. As she cuts a brain from its head, Cam confesses that she slept with Grayson. Should she tell Angela? Grayson is still in town and Cam is seeing him again but she feels guilty. Sweets believes she should tell Angela. Angela is open-minded and in a committed relationship. Cam agrees. She lets Sweets touch the brain as a reward. Angela enters with news that Wexler is dead. Cam rushes off to inform Hodgins and Clark. Unsupervised, Sweets touches the brain again.
At Oxford University, Brennan and Cate give the news to Wexler's students. They're devastated, especially Vera and Cyril. The team speaks with them first. Vera and Cyril saw Wexler two nights before. He was upset because Roger Frampton was trying to shut down his dig in order to build a condo.
Legally, Wexler's remains must stay in England but casts of the bones will be shipped to the Jeffersonian. Hodgins will receive particulates as well. Angela is concerned about Brennan but Brennan says she is trying to stay focused. Angela gives her the news about Grayson and Brennan congratulates her on the divorce. After they hang up, Brennan finds a melted plastic poker chip marked HGC on the remains.
HGC stands for "Highgate Gentlemen's Club." Wexler was at the club two nights ago drinking and gambling. He paid off his entire tab of 5000 pounds in cash. Cate presses the manager further and he produces security footage of two men dragging Wexler from the club, one with a tattoo on his wrist.
At the lab, the tox screen shows that Wexler was heavily inebriated. No nicotine was present. The cigarettes were a set up. Clark finds evidence of strenuous repetitive motion. He also believes that a head-butt caused the fracture on the frontal bone. Cam blurts out that she slept with Grayson. Clark tries to make a hasty retreat but Cam grabs him for moral support as he cringes. Luckily, Angela is not upset. "I got what I wanted from him so now I guess you did too." Hodgins arrives for the end of Cam's sordid tale. He also learns that Grayson is still in town but why should they care? Hodgins reports that the particulates on Wexler's clothing indicate he was by Henley-on-Thames, a popular rowing site, within 24 hours of his death. It could explain the strenuous repetitive motion.
At Henley-on-Thames, Booth and Brennan question LAKE and PALMER, Wexler's rowing teammates. They are unimpressed with Booth's FBI status. They hint that Wexler and Cate were more than just partners. Booth notices a tattoo on Lake's wrist, the same tattoo from the club's security footage. The men admit to dragging Wexler out but only because they had to sober him up for a race. Palmer and Lake tell them JASPER FERRY, a member of another crew team, head-butted Wexler.
Booth attempts to question Jasper but as Royal Guard, he is forbidden to say anything: literally. Cate meets them and threatens to arrest Booth for interfering with the Queen's Guard. She assures them Jasper did not kill Wexler. He head-butted him because Wexler was sleeping with his sister.
At the lab, Cam thanks Sweets for his excellent advice. At first, she found it hard to take him seriously but it turned out that he was correct about telling Angela the truth. They approach Hodgins and Angela. Cam asks them for results on the other particulates and the enhanced photos. They both brush her off and walk away. Sweets deduces that there may still be "unresolved issues."
In London, Brennan and Booth confront Cate. She admits she slept with Wexler but she didn't kill him. He was so good in bed because of all the other women he'd "practiced" with. It wasn't a motive. Clark and Cam call to inform them that Wexler was stabbed to death. Did Cate come across a possible murder weapon at the crime scene? She says no but Booth and Brennan doubt her.
Cate tells Brennan that Wexler was not her only sexual partner. She is sure Brennan was also seeing other men besides Wexler. Brennan explains she never slept with Wexler. Booth was against it. "I suspected that you two might be more than just partners." Brennan corrects her. She simply values Booth's opinion. Cate was afraid her relationship with Wexler might have gotten her kicked off the case so she didn't disclose it. She produces a writ-of-release signed by Wexler. It states that the dig site was worthless. This document means Frampton could begin building his development. Could Frampton have forced Wexler to sign it before murdering him? Before they part, Cate suggests that Brennan consider the possibility of a relationship with Booth.
Once again, Booth and Brennan interrogate Roger Frampton. He is offended that they think he would commit murder when his daughter was recently murdered. He asks them to leave so he can get "blind drunk."
On the phone at the lab, Hodgins reports his new findings directly to Brennan. There was mercury fulminate on the victim but he needs more samples to determine what this means. Brennan says all requests for evidence must come through Dr. Saroyan. Hodgins is annoyed that he can't move forward without Cam. Sweets holds a meeting between Cam, Angela and Hodgins to relieve the tension. He helps them all apologize to each other as only a "highly trained mediator" can.
Back in London, Vera and Cyril are shocked that Wexler signed papers stating the dig site was of no value. They have to vacate in two days. Cate appears with evidence that Frampton bribed Wexler to sign off on the site in return for 25,000 pounds.
At the lab, Clark and Hodgins conclude that the mercury fulminate was on the murder weapon and was transferred to the body during the attack. The murder weapon was rough, almost like a stick.
In England, Brennan goes over the remains again and reports that an extra bone, the shattered section of a femur, was found with Wexler's remains. This is the murder weapon and it's two thousand years old, making it true a Bronze Age artifact. The dig site did have historical value.
Hodgins and Angela eat at the Royal Diner. They talk about their meeting with Sweets. "Did you understand you weren't actually mad at Cam?" Angela was mad at her though. Hodgins doesn't understand. She and Grayson are divorced. Angela counters, asking why Hodgins is uneasy with Grayson still being in town. Hodgins insists he doesn't care. Angela has a realization: Hodgins doesn't trust her. Hodgins realizes something too: Angela doesn't trust him. If she did, she wouldn't have come to her conclusion. Their hearts sink. "How can two people who don't trust each other get married?" Angela decides to leave. Hodgins doesn't stop her.
Back in London, Brennan discovers that the mercury fulminate came from a seventeenth century tannery located on the dig site. Tanneries use mercury fulminate and it seeped into the soil.
Vera managed that part of the site but it is covered with a tarp. Brennan and Booth uncover the area. They find a Bronze Age bone chip, further proof that the site is real. Vera insists that Wexler instructed her to cover the spot. Brennan realizes the murderer would have cut their hand since the weapon had no hilt. Vera hides her hand and tries to run. Brennan trips her and Booth cuffs her. Cate puts the pieces together. Wexler and Vera took the bribe but then made the find. Wexler wanted to return the money but Vera knew her career would be ruined when everyone found out she'd accepted a bribe.
Angela calls Brennan to tell her she and Hodgins broke up. Grayson returns in case Angela changed her mind about their relationship. Clark decides to take Grayson to the airport and he is never coming back. This lab has too much drama for a man of pure science like himself.
In London, Cate meets Brennan and Booth to say goodbye. She knights Booth with a dinner knife and gives him a junior knight medal from a toy store. Booth is nonetheless touched. Brennan suggests they leave before someone else gets killed. "Sir Seeley" extends his arm and leads Brennan away.