We open at the gun range, where FBI agents take their best shots. "Heard you could shoot a hole through the middle of a dime on the run," an agent named Carson says to Booth. Not this time. Booth's target comes back showing all near misses. Booth then heads to the scene of a collapsed water main. "I don't know if I'm going to make the grade," he tells Bones of his marksman recertification test. "Maybe this is all about my brain tumor." Bones dismisses the theory, suggesting the problem is psychological. Inside the sinkhole, B&B discover a tiny skeleton -- a bright green one. "Why don't you get Darby O'Gill out of there," Booth cracks.
Back at the lab, Hodgins explains that iron oxide in the soil turned the dwarf skeleton green. The victim was also killed about three months ago. Bones and Nigel conclude that the dwarf was strong -- perhaps even a wrestler due to the evidence of injuries. Angela runs the bone structure through her computer and comes up with a match. The victim was a "midget wrestler" called the Iron Leprechaun. "So it was a leprechaun," Angela quips. The only problem: a Web search reveals that the IL is scheduled to wrestle tonight. Booth, in the meantime, goes to a restaurant to visit Gordon Wyatt, who has traded in psychiatry for cooking. "I need some advice," Booth says. "Pretend I'm a recipe that needs fixing." Booth explains that the can no longer shoot straight. Gordon agrees to tag along to the wrestling match in order to further examine Booth. Cut to a small venue, where the IL is beating up another dwarf in a bee outfit. After the match, Booth climbs into the ring to question the wrestler, who runs. It's no contest. Booth drops the dwarf like a bad habit.
Moments later, the leprechaun is being questioned by Sweets, Booth and Gordon. He explains that he took over for the previous Iron Leprechaun about three months ago. "We found his body at the bottom of a sinkhole," Sweets tells the wrestler, who is SHOCKED. The dwarf explains that he ran from the FBI because he is an illegal immigrant from Canada. He then suggests the team pay a visit to the promoter, a dwarf named Gidget. "They used to bump uglies and it didn't end so great." Seconds later, Booth and Bones pay a visit to Gidget, who denies killing her ex boyfriend. She does say that her pistol went missing about the same time the original Iron Leprechaun disappeared. Interesting. Back at the lab, Nigel has discovered a series of small grooves on the victim's ribs, but can't explain what they mean yet. The team then brings in the full-sized brother of the victim, Derek, who explains that his sibling, who had a history of criminality, "testified against his cellmate in return for parole." Derek's wife defends her dead brother-in-law when Booth makes a size crack. Hmm.
Sweets and Gordon, who have agreed to consult with each other about Booth, question the victim's cellmate, who explains that he was never upset with the dwarf for tattling. In fact, the cellmate understood the victim's need to get out of prison as he had recently received a "dear John" letter from Gidget. Back at the scene, Hodgins has found tile dating back to the 1930s -- an underground passage! Using old planning maps, Booth quickly traces the passage to the basement of nearby gold exchange shop. Turns out that shop was robbed three months ago, losing about $150,000 in coinage. Back at the lab, Bones and Nigel think they might have something. The victim was likely shot while in the underground passageway. "One bullet, fired from above, grazing these three ribs," Bones says. "We found cause of death!" Cut to the bar, where Sweets and Gordon discuss Booth's inability to shoot straight. Bottom line: they think it has to do something with the lack of getting it on with Bones. "Booth not shooting straight is simply a manifestation of his phallic frustration," Sweets suggests. Says Gordon: "He quite literally can't bring his weapon to bear."
In the meantime, Gidget is brought back in for questioning. She admits that her stolen gun matches the one found at the crime scene. "Did you give Brice the gun because you knew he was planning a robbery?" Sweets asks. Gidget will only say that her ex beau claimed to have found a way to make a "ton" of money. Also: Gidget denies being the author of the "dear John" letter. There was apparently another lady in the victim's life -- a full-sized one at that. "He said I wasn't enough woman for him," Gidget says. Gordon and Sweets believe they have it all figured out. They explain to B&B that the victim was pining for none other than his brother's wife! Wasting little time, Booth takes the woman to the crime scene. "He was doing it for you, wasnt he?" Booth asks. The woman admits to the longtime affair with the dwarf, but still doesn't know who killed him. Back at the lab, Hodgins has found a high-school wrestling ring. "This is not the victim's ring!" Bones says. So whose is it? Turns out that brother Derek wrestled in high school -- and he certainly has a motive if he suspected his wife of cheating. Sure enough, the ring fits. Derek planned the robbery with his brother, then shot him dead once it was completed. Revenge of the cuckold, in other words. Case closed.
But not the episode. Booth is still fretting to Gordon about having to take the marksmanship test. "When you were in a coma, you got a glimpse of another world," Gordon says. "It's Temperance Brennan. You're in love with her." His psychiatric advice: take Bones to the recertification test. "You won't fail in front of her," Gordon says. "Trust me." Sure enough, Booth does just fine with Bones in the audience -- all perfect shots. Bones gives her partner the thumbs up.