Tracey and Michael are lost in the woods. Manly Michael refuses to admit that they are lost, and continues to look for a trail. It starts to rain. The couple runs for shelter in a nearby cave. Inside they find two bodies holding each other, covered in maggoty death.
Booth and Brennan meet Ranger Gary Nesbitt on the scene. Booth and Gary immediately hit it off, both former men of the service. Gary reveals that his brother wasn't as lucky as them to return home. Brennan asks Booth about Hannah's next assignment. Booth assumes she will be somewhere in Iraq. Inside the cave, Brennan identifies the victims as a male and female in their thirties. Both bodies suffered multiple fractures; the woman's being more serious. Brennan thinks they may have been bludgeoned but wants the remains, rocks, and soil transported back to the lab.
Booth and Brennan grab lunch at the Diner. Booth and Brennan discuss how great it is to be working together again. Booth sees girlfriend, Hannah Burley, suddenly enter the Diner. She has been relocated to D.C. The two kiss hello, as Brennan jumps in to introduce herself.
At the lab, Dr. Clark Edison is back working with Dr. Brennan. Brennan notices that most of the female fractures are localized to the left posterior side as well as multiple breaks on the femur, pelvis, and vertebrae. Hodgins finds traces of fossiliferous limestone, leading Cam to believe the assailant struck the victim with a rock. Brennan tells Cam and Angela that Hannah is mathematically pretty.
Booth brings Hannah to his office, and gives her a key to his apartment. Their reunion is interrupted when Gary Nesbitt knocks on Booth's door. Gary gives Booth a file of a murder that happened in the woods about ten years ago.
Angela comes to see Hodgins. Hodgins is busy vacuuming the victims' nose for pollen to help him determine time of death. Angela shows him the reconstruction of the victims' faces. The female, Hillary Fuller, is a pretty blonde, and the male shows a strong resemblance to George Clooney.
Meanwhile, Sweets sees Booth at the FBI and tries to get him to talk about Hannah. However, Booth is tight-lipped. He goes to the Conference Room to talk to Jerry Doroughty, Hillary's old boss who reported her missing. Booth shows Jerry the picture of the male victim, but he cannot identify him.
Angela and Brennan watch one of Hannah's news reports on the Angelatron. Hodgins comes in and is surprised with how attractive Hannah is. When Angela prompts him for relevant information he tells them that the couple died on the 13th, two weeks ago.
Back in the FBI Bullpen, Booth shows Brennan a mug shot of Winston Hinkle. Hinkle is the man responsible for the murder in the woods years ago. Booth tells Brennan he was just released from prison two weeks ago and lives outside the park.
On their way to talk to Hinkle, Sweets notifies Booth that Hinkle has a history of bipolar and cyclothymis disorder. Sweets fails again when he asks Booth about Hannah. They reach Hinkle's cabin and ask Hinkle about the murdered couple. Hinkle tells them he didn't do it. Sweets believes he is telling the truth.
In the Lab, Cam reveals that the female's left posterior ribs shattered causing them to pierce her lungs, kidney, and heart. The male's injuries weren't as severe, but he did have internal bleeding. Brennan questions why the male victim didn't leave to get help, and why his injuries are localized to his front and hers are localized on her back.
Hannah, Booth, and Brennan have lunch together. Hannah tells Brennan how Booth saved her life in the field. Hodgins calls Brennan to tell her that he found insect eggs on the male victim. The eggs belong to wingless aphids that exist in windy environments at high altitudes. Booth and Brennan decide to go back to the woods for some answers.
At the park Gary Nesbitt, Booth, and Brennan search a cabin fitting Hodgins description. Brennan finds the initials "FV loves HF "and the date 9/13 carved into the wood.
In the Lab, Clark has discovered traces of nicotine on the male victim's hands, leading him to believe that FV was a migrant worker who picked tobacco. However, the female victim, Hillary Fuller, was a well-educated woman who worked at a marketing firm. Clark wonders what these two people have in common.
Over lunch at the Diner, Brennan, Sweets, and Booth discuss the couple's different backgrounds. Brennan admits that even though they are very different, she used to imagine herself with Booth. Brennan gets a call from Clark and Cam in the Lab. Cam has found that both victims had a low bone mass and suppressed bone formation, showing that they were both alcoholics. They have found the missing connection between the two victims. Booth believes they met in AA.
Booth and Brennan attend the victims' AA meeting. They meet Lorraine Allen, who knew Hillary. Lorraine tells them that FV was Felix, another member who Hillary sponsored. The two had become romantically involved, but Felix's girlfriend was jealous of their relationship.
Booth interrogates Lupe Rojas, Felix's girlfriend. Booth is surprised that Lupe isn't upset about Felix's death. Lupe admits that her relationship with Felix was a waste of time. She tells him her allergies would have prevented her from ever going to the woods.
Booth and Hannah lay in bed together after a little afternoon delight. Hannah admits to Booth that she is jealous of his action packed relationship with Brennan. Booth assures her that there is nothing romantic between him and Brennan, and hopes that Hannah stays out of trouble when she is out looking for action.
In the Lab, Hodgins receives Lupe's car tires to see if she lied about going to the park. Clark determines that the couple fell on the rocks. Hillary broke Felix's fall, which is why her injuries were more severe than his. Angela shows an animation recreating the fall. A section of rocks at the park matches the injuries about two hundred and fifty feet away from the cave.
Booth and Brennan return to the park and find the rocks Angela described. Brennan notices a high lookout point from where the couple may have fallen. Hodgins calls to say he found evidence in Lupe's tire treads that she was at the park.
Booth brings Lupe into the Lab for a Hodgins experiment. Hodgins has brought in different plants that are found in the woods. If Lupe is as allergic as she says, her alibi will hold. Lupe violently reacts to the dogwood, and coincidently so does Clark. As the two have a sneezing fit, Cam comes in with news.
Cam shows Booth and Brennan the remaining flesh on Felix. All the flesh has been eaten off by parasites except for areas around the eyes and cheek. Cam has found traces of pepper spray that the bugs wouldn't eat. Booth realizes that the Forest Service issues spray to park rangers to fight off bears or other animals.
Booth and Brennan question Park Ranger Gary. Booth reveals that Felix's record shows that he bought alcohol for a minor: Gary's niece. She then died in drunk driving accident. When Gary saw Felix in the woods, he took the opportunity to get revenge.
Booth and Brennan have a celebratory drink at the bar. They are discussing their different views of love when Hannah walks in the door. Hannah and Booth leave for their dinner reservation while Brennan is left alone to finish her drink.