A pair of British chemists are checking for contamination in a river in Paraguay when they discover, much to their horror, a hand and several other severed body parts.
The hand is quickly identified as belonging to the US Navy SEAL, Petty Officer Matthew Dean. At first, the team is confused as to what Dean was doing in Paraguay, as military personnel had orders to stay out of the country.
Initially, they suspect he was there for extreme sports, but his wife thought he was in Canada on a fishing trip. Then the team discovers that a friend of Dean, Petty Officer Hudson, is missing.
Ducky discovers that while the hand belongs to Dean, all the other body parts belong to Hudson. Dean is still alive and still in Paraguay, possibly trying to steal money from local self-proclaimed rebels.
Gibbs, Torres, and McGee head down to Paraguay and find Dean, who reveals that he and Hudson were actually trying to rescue the son of a local villager who had helped save the SEAL team on their previous mission.
The man's son had been kidnapped by the "rebels" so they could turn him into a child soldier, and Dean is determined to finish the mission to save him.
A coordinated rescue attempt is successful, but Gibbs and McGee stay on the ground to cover the others' escape in a helicopter.