The show starts with a mother being notified by the Navy that her daughter Catherine Quinn was killed in action, caused by an IED in Kandahar.
Secretary of Defence contacts Vance to get his help in locating Sean Quinn. They need his bone marrow to help save his brother Alex Quinn, who is dying of leukemia.
Sean Quinn became estranged from his family six months ago.
Tony and McGee check out Sean's apartment, and find $100,000 in counterfeit cash, and a bunch of passports.
Tony reveals that Sean has been trading in the fake dollars for real cash at various casinos.
Fornell shows up. Vance tells Gibbs that the FBI and Secret Service have been tracking the counterfeit scheme for a year.
Fornell tells the team that Sean came to the FBI as an informant after Thomas Reynolds' body was found in the river with a bullet in his head. Reynolds was Sean's friend from high school. He recruited Sean into the counterfeiting gang.
Fornell tells them that Sean is needed in order to get to the inner circle of the ring, and that he can't be pulled out to provide a blood sample. He offers to take Gibbs to Sean at a safe house.
Bishop's brother George helps Bishop through her marriage woes. He notes that she's still wearing her wedding ring. She says that marriage isn't something you give up on.
Ducky, Gibbs and Fornell go to the safe house. They find a car with a dead FBI agent in the car. Sean is missing.
Bishop hacks into the donor base to find out the contact information for a bone marrow candidate - Richard Doogan - who refused to provide marrow for Quinn. She discovers that he's serving a life sentences for a double homicide, and that he's in the Leavenworth disciplinary barracks.
Abby discovers that the bullet which killed the FBI agent also hit Sean.
Bishop interviews Doogan in prison, who agrees to provide his bone marrow. His condition is that he would like his life sentence reduced to time served.
Sean's mother tells Gibbs about a boat that Sean used to work on, as a possible place for him to hide out.
Tony and McGee visit the boat's storage unit in search of Sean. They find Sean unconscious in his boat.
Tony tells Gibbs that Sean isn't a viable donor for his brother. The only real candidate is Doogan.
Abby used casino video to discover that Sean's apartment building manager Alton Brinkman had been doing the casino runs before Sean started.
Gibbs and Bishop travel to prison to provide a counter-offer to Doogan: in return for his bone marrow contribution, his life sentence stands, with the possibility of parole (which he didn't have before). He rejects the deal.
Tony and Fornell interview Brinkman. After Tony presents evidence that he shot the FBI agent and Sean, he offers to give up his boss Malcolm Turro.
FBI surround Turro and his gang. Fornell points his gun at Turro and tells him to put his gun down. Turro starts to raise his gun, but Tony comes up behind him and knocks him out.
Bishop interviews Doogan again. She talks him into taking the deal.