 Five-O intercepts a "box man," an expert safe cracker, at the Honolulu airport. The criminal is killed by a shot from Dan Williams, who fired just before the criminal would have shot Chin Ho. The man had $20,000 and instructions to check into a hotel on Hilo. McGarrett goes undercover, posing as the box man. The lawman finds himself involved in a conspiracy involving two other criminals, Swanson and Andre, as well as a woman. All claim to know nothing about "the Man" who is sending them instructions. Eventually, McGarrett discovers the target of the plot -- a yacht where a diplomat of another nation is staying which has six kilos of heroin in a very secure safe. (This episode apparently takes place before episode 1.16, "The Box," where Swanson appears as an inmate in Oahu State Prison.)