While Five-0 races to stop a mad bomber before he kills again, Danny gets an unexpected visit from his little brother, Matt, a fun-loving, Wall Street broker. The family reunion is cut short, however, when Danny discovers the real reason that Matt is in Hawaii.

While hiking in a remote area of the jungle to see the famed petroglyphs, McGarrett and Danny instead find a homicide victim. Meanwhile, their aunt's failing health leads Kono and Chin Ho to visit home, where Kono finally learns the truth about the scandal that ended her cousin's career with the Honolulu Police Department.