As Brennan anxiously prepares to leave Christine for the first time, the Otton family drives down the interstate, bickering as they begin a family vacation. Their car hits a bump in the road and their luggage dislodges from the roof. They try to gather their belongings when they realize the "bump in the road" is actually a dead body.
Meanwhile, Cam and Finn grab breakfast at the Royal Diner. Cam urges Finn to have some fun instead of working all the time. He should go on a date. But first, she sends him to prepare the Lab. They have a case.
On the Interstate, FBI Techs lift the remains from the road with spatulas. Brennan tells Cam she instructed the Jeffersonian Day Care to send her a picture of Christine every half hour. They all admire a picture of the baby after Brennan determines the victim was an African American female. This seems like a hit-and-run until Brennan mentions the skull is missing. It was removed before the victim was left on the road. She takes a picture of the bones to send to Finn but accidently sends it to the Jeffersonian Day Care. Oops.
At the Lab, Finn and Hodgins determine the victim's head was torn off and she was dragged down the highway. Brennan notes that the bones are stained with diesel fuel. There's also grease on her clothing. Finn puts it all together: the victim was dragged by an eighteen-wheeler.
At the FBI, Agent Genny Shaw tells Booth she was able to determine exactly which eighteen-wheeler dragged the victim. The body was found between a scale embedded in the road and a weigh station. A Fields Market truck weighed 122 pounds more when it crossed the scale then when it pulled into the station. It must've been dragging the victim.
Hodgins and Angela analyze degraded pieces of paper from the victim's pockets and bra using an Ultrasonic Bath and a Video Spectral Comparator. Though Hodgins believes these papers are important, they turn out to be nothing more than coupons: 10 Cents Off Any 3 Pack of Tapioca Pudding!
In the Autopsy Room, Cam runs a tox screen. Finn reports that he hasn't found a COD. He'll need to reassemble the skeleton. Michelle Welton unexpectedly arrives to give Cam her car keys. Finn is instantly taken with her. Michelle and Finn flirt and walk away together much to Cam's dismay.
Booth and Brennan question Alan Bates at a Loading Dock. He drives the Fields Market truck that was carrying the extra 122 pounds. Bates is annoyed and doesn't have any idea about a dead body. Brennan grabs a dolly to survey the undercarriage of his truck. She finds flesh, sinew and the victim's head lodged in the driveshaft!
Bates swears he didn't kill the victim. Brennan finds panties inside his truck so Bates reluctantly admits he wears them while on the road. If they won't tell his wife, Booth can have his logbook to see where he has made deliveries.
In the Autopsy Room, Hodgins, Cam and Angela prepare to make the dead head sneeze. Hodgins thinks they can use the pollen that the victim inhaled to determine where she took her final breaths and pinpoint where the truck picked her up. Angela is excited about Finn's date with Michelle but Cam has reservations. ACHOO! Cam forces mucosa out of the victim's nose with compressed air. Gross!
Booth and Brennan visit Christine in the Jeffersonian Day Care. Brennan shares that the victim's hair got caught in the driveshaft, which bored a hole into her brain and caused her death. But why was the victim crouching under the gears of the truck? Booth thinks she was hiding from someone. Hodgins arrives with the results from the dead head sneeze. The mucosa contained pollen from a Chestnut Farm in Hagerstown. Bates didn't make a stop there but Booth believes someone there may know the victim.
At the Chestnut Farm, Booth finds the victim's husband, Dale Berquist. He's shocked to hear that his wife, Barb Berquist, is dead. Booth mentions there were coupons stuffed in her clothes. Berquist brings Booth to the basement to show him "Barb-Mart:" the space is filled from floor to ceiling with food. She was an Extreme Couponer. Barb would go shopping and be gone for days. Berquist last saw Barb as she was heading to Fields Market in Frederick.
At Fields Market, Booth speaks to Manager Chad Fergus. Barb was his best customer. Fergus leaves Booth to help his cashier, Crystal. She's dealing with an Extreme Couponer, who is trying to use expired coupons. Fergus voids the coupons with the purple marker from his clipboard. Brennan approaches with several bone fragments. She found them in the parking lot. Booth asks Fergus to talk privately. Fergus shows them last night's security footage: Crystal and Barb had a very heated fight.
Booth and Brennan bring Crystal into the Interrogation Room. Crystal explains that after the fight she counted out her drawer while Fergus cleaned up the mess. Crystal doesn't care that Barb is dead. Barb and her Extreme Couponing Club ruined Crystal's life. Barb told them all to go to her checkout line because she was the fastest and Crystal injured her wrist. They should talk to the Couponing Club.
At the Diner, Sweets notes that couponing is like an addiction while Angela hacks into the victim's email account. Barb received heated emails and threats from someone called "Deal Diva." It looks like the Couponing Club has a meeting tomorrow.
Finn and Michelle walk home after a bluegrass concert. Finn wonders if they can spend more time together this weekend. Michelle kisses Finn and says yes.
Cam checks in on Finn. She's very upset to see that Finn has not reassembled the skull. Finn asks Cam if her anger is really about him spending time with Michelle but Cam denies it. Suddenly, Finn notices an abrasion on the frontal bone meaning the victim was hit on the head before the truck killed her. Finn tells Cam that a wide V-shaped tool may have been the murder weapon. Cam tells Finn to have Hodgins swab it.
In Angela's Office, Brennan sees that her friend is hiding something. Angela snuck Michael Vincent into the Lab and put him in one of her filing cabinets. Brennan tells her she has to compartmentalize her life even though she's having a tough time practicing what she preaches.
Sweets and Booth attend the Couponing Club where they find dozens of women fighting over coupons. Booth asks to see the Deal Diva. Rhonda Fitzgibbons steps forward with her metal index cardholder. Sweets notes that her holder could be the murder weapon. Booth asks to see it and Rhonda resists. Booth cuffs her and her coupons go flying. They're quickly devoured by the other Extreme Couponers.
Booth and Sweets question Rhonda. She tells them that she and Barb used to be best friends but after Rhonda introduced her to couponing, Barb turned into a monster. Rhonda explains that two weeks ago she wouldn't give Barb a coupon and Barb bashed her head into a shopping cart. Rhonda hands them a huge stack of receipts to show that she wasn't at Fields Market the night Barb died.
Michelle comes into the Autopsy Room looking for Finn. She bought him lunch. Cam tells Michelle she doesn't want her to see Finn anymore. Michelle angrily replies that she is eighteen and can make her own decisions.
In Booth's Office, Agent Shaw reports that Barb and her husband have a joint credit card. She noticed that on the nights Barb was out shopping, he would be using the credit card at expensive restaurants. Agent Shaw asks Booth how Brennan is doing, and Booth is surprised when Shaw reveals she is a mother herself.
Brennan and Finn look at the skull reconstruction. Brennan notices a metal fragment embedded in the wound. Finn notes that the metal is aluminum, which rules out Rhonda's card case as the murder weapon.
In the Interrogation Room, Booth grills Barb's husband. Berquist admits he was cheating on his wife. He was fed up with the Extreme Couponing. Barb would rather dumpster dive for coupons than spend time with him. He insists he was innocent and was about to come clean about his affairs. But Booth doesn't believe him.
In the Autopsy Room, Finn approaches Cam. He respects her and agrees to stop seeing her daughter. He already told Michelle but she was less than understanding.
In the Bone Room, Finn tells Brennan that none of the tools from the Berquist Chestnut Farm are a match for the murder weapon. He did find a puncture to the bone and there's hemorrhagic staining. Hodgins swabs it and determines that it's not blood. It's purple ink. Brennan knows who the murderer is.
Booth and Brennan return to Fields Market and walk the aisles looking for Chad Fergus. Brennan remembers Fergus used a purple marker to cross out expired coupons. They confront him and Brennan finds a bone shaving in his clipboard, which is the murder weapon. Fergus admits he attacked Barb. He was sick of her Extreme Couponing. He wanted Fields Market to be a high-end establishment. But he didn't kill her. Booth tells Fergus he committed a felony assault, which resulted in her death. He's guilty.
At the Lab, Michelle cries to Cam about Finn. She is angry that Cam forced Finn's hand. Finn arrives to tell Cam he cannot stop seeing Michelle. He won't walk out on her. And if that means he loses his job... so be it. Cam tells Finn he isn't going anywhere. Michelle and Finn embrace, kiss and walk off together. Oh, young love.
Brennan and Booth enjoy some quality time with a sleeping Christine. Brennan finally reveals to Booth that she is struggling with being separated from Christine. Brennan knows she has to do her job. It's important and Christine should know that but Brennan is going to have to sneak Christine into the Lab. Booth supports this decision.