McGarrett investigates the death of a friend when it becomes apparent that the man did not drown as was commonly believed.
McGarrett's investigation of an old friend's drowning points to a foreign ship moored in a Hawaiian harbor.
The Hawaiian governor assigns McGarrett to break a ring of con artists swindling visiting rich widows; guest Kevin McCarthy.
An official's death involves strange clues, including a woman with a camera and a man with a briefcase; guest Simon Oakland.
A publicity stunt by a rock singer (Sal Mineo) to stage his own kidnapping backfires when ransom is offered; guest Sam Melville.
McGarrett must protect an underworld kingpin (Ricardo Montalban) he is trying to convict of racketeering activities.
The Five-0 team works overtime when Danny is indicted for the murder of an apparently unarmed teenage boy; guest Gavin MacLeod.
The owner of a tuna boat uses his craft to smuggle gold bars into the islands; guest Paul Richards, Marj Dusay.
McGarrett goes under cover in a California prison to find the connection between a girl's death and the theft of a gem collection.
A singer (Tommy Sands) turns to cat burglary when his musical efforts fail to satisfy his mounting gambling debts.
An Army corporal is accused of a crime after a winning ticket in a numbers game turns out to be a loser; guest James McEachin.
Danny takes over and starts a desperate search for clues after McGarrett is felled by an unknown assailant.
Five-0 fights to save the life of gangster so that he can testify against his boss; guest Nehemiah Persoff, James Shigeta.
A large footprint and a circular mark made in mud provide Five-0 with the only clues to a lovers' quarrel that turned into murder.
A Marine veteran (Yaphet Kotto) suffers a breakdown and, believing he is back in Vietnam, takes Danny hostage in a hospital ward.
A girl dies under the influence of drugs possibly supplied by a self-proclaimed guru; guest Ed Flanders.
A man carrying bubonic plague arrives in the islands the same time as plans for a top-secret weapon vanish; guest Jackie Coogan.
McGarrett offers himself as a hostage in an attempted prison break by two ``lifers''; guests Gavin MacLeod, Gerald S. O'Loughlin.
Employees of a family-owned business are threatened and the company's matriarch vanishes; guests Farley Granger, Jeanette Nolan.
A policeman wants to avenge the murder of his son, a prizefighter paid to fix a bout; guest Jesse White.
McGarrett travels to Los Angeles to investigate a physician who is victimizing his sister and her child.
Despite public sentiment and a lack of damaging evidence, McGarrett takes Dr. Fremont (Joanne Linville) to court.
McGarrett must determine whether the leader of a peace movement who was shot and killed was the assassin's intended target.
Chin Ho and Dan Williams are tracking a safecracker but he pulls a gun and Danno ends up shooting him. McGarrett takes the identity of Harry Brown and must infiltrate a sophisticated gang of international thieves.
Visions of an ancient volcano goddess figure in plans to kill an old man to gain control of his land; guest Sally Kellerman.
