Contains spoilers for this episode and earlier episodes.
Farmer Harold Clark parks his tractor near the Treasury Department and demands attention while claiming to have a bomb. The Lightman Group's offices fall inside the danger area, trapping a visiting class of children. Loker keeps the pupils occupied as Lightman studies Harold and argues with the FBI over whether he is preparing an attack. The search extends to Harold's farm and the associates who share his anger about losing it.
Ron Jackson has threatened Harold's family and forced him to sit over a supposed dead-man switch. Torres helps secure his wife and son, while the investigation identifies a separate van bomb near an economic summit. Harold's public confrontation is a distraction from Jackson's real target. Lightman and Reynolds locate Jackson and stop that attack, but the FBI still intends to destroy the tractor's supposed explosives with a device that could kill Harold.
Lightman questions an accomplice's insistence that Harold has a bomb and concludes that the remaining threat is a bluff. He walks out to the tractor despite the FBI commander's refusal to guarantee his safety. Harold climbs down, and the feared explosion never happens. Inside the office, the children finish a song with Loker and their teacher. The boy who stole the class turtle also confesses, explaining that he thought the animal would be lonely at school overnight.