An ambulance arrives at an apartment building. When the attendants rush to the second floor, several students dressed in uniforms jump in and start to drive the vehicle away. One of the attendants rushes downstairs and tries to stop the ambulance, but it runs over him.
Several high-IQ students known as The Brain Trust are plotting strategy for a multimillion dollar theft. When one of them says that memorizing all the details of the plan is like cramming for a final, their leader Ted Bonner (Leigh McCloskey) says it's a "six million dollar final."
The ambulance is stored in a warehouse-like building. One of the students, Kenji Tatsumo (Ron Nakahara) is worried about the attendant who got run over. He says the rest of them can count him out of the plan. Shirley Collins (Ayn Runeman), one of the leaders, apologizes, but Kenji says that she is not sorry, and she "enjoyed it," and that he doesn't want a murder rap pinned on him if the man dies. After Kenji leaves, Shirley and Larry Marsh (Jim Simpson) follow him to the Iolani Palace. As he mounts the steps heading for the Five-O office, Shirley pulls out a gun with a silencer and shoots him dead.
McGarrett is understandably annoyed that there someone was murdered right outside his front door, and there were no witnesses.
Ted is also not happy about the shooting. Shirley sucks up to him, saying that Kenji was "going to put us in jail to save his own neck." They decide to keep details of the shooting from the other members of the plan. Larry, an expert in geophysics, takes Kenji's place in the scheme.
Williams and Chin Ho talk to the dean of the university about Kenji. They arrive at the Brain Trust house where Chin checks Kenji's room and finds a rifle, some terrorist propaganda and a manual on plastic explosives. Ted tells Danno that Kenji was "quiet recently," and feels guilty because he never talked to him much.
Duke reports to McGarrett after talking to Kenji's family, discovering that he had no interest in guns and was a member of the anti-war movement. McGarrett says that Che Fong found no fingerprints on the rifle. McGarrett order his men to "check every militant organization on campus for links to Kenji."
The next morning, Ted wakes early. He is upset that his plan isn't going so smoothly. Shirley strokes his ego, offering to drop out of the plan, but Ted quashes this idea.
Later in the day, the two of them drive to the Honolulu Observatory of the National Weather Service. Wearing masks and gloves, they enter, much to the surprise of the chief forecaster, Ron Bradford (Sid Clute) and the other employees. Ted and Shirley lock the two other employees in a back room and smash Bradford's glasses, knowing that he can barely see without them. They order Bradford to issue a report for a tsunami (tidal wave) which will hit Honolulu at 3:22 p.m. Bradford says they are "crazy," that the military will figure out the report is false within a couple of hours. Ted says that's all the time that they need.
Dr. Dimitri Sartain (Lyle Bettger), in charge of the tsunami warning system for the entire Pacific area, is emerging from church when he gets a page about the impending tidal wave. He confirms the report with Bradford, who is being held at gunpoint.
As sirens wail throughout Honolulu, people at the beach are evacuated. Five-O is asked by the Governor to coordinate with military and civil defense. The civil defense trucks travel through neighborhoods announcing the warning in multiple languages. People in hotels are seen freaking out.
Members of the "Brain Trust," under the direction of Larry, prepare for action, putting on ambulance attendant uniforms.
McGarrett and Dr. Sartain appear on TV, telling people to follow instructions from the authorities. Sartain says the wave will approach at up to 600 miles an hour, and there will be not just one wave, but a series of waves. People are urged to move to high ground.
At the observatory, Dave Keller (David Palmer), one of Bradford's associates, arrives by truck, but Bradford is able to get rid of him. Back inside, Bradford cuts the phone cable when Ted and Shirley aren't looking.
Members of the Brain Trust head away from their house in a car painted to look like a police vehicle.
Historical pictures of tsunami damage such as befell Hilo in 1958 (the actual date was 1960) are shown on TV. There is news of panic in some of the luxury hotels. Sartain and McGarrett take a helicopter ride over the threatened area, which is almost totally deserted. Sartain says the wave, which is expected shortly, could be 100 feet high and could go up to a quarter of a mile inland. People are watching from the hills behind Honolulu.
Brain Trust members pretending to be cops head to a now deserted shopping area.
Danno reports to McGarrett that there is no confirmation of the seismic occurrence from the military. Sartain stresses that Bradford is a total professional whose word can be trusted.
The Brain Trust members enter a jewellery store. When the alarm goes off, real cops from HPD drive up, but the bogus Brain Trust cops say they have the matter in hand, and that they'll "take these suspects in." When the real cops depart, the students smash display cases and dynamite the safe to grab as much loot as possible.
McGarrett meets Danno at a landing pad near Diamond Head, saying that he has a "hunch." At the observatory, they find Bradford suffering from the effects of being knocked out. He can't give them much of a description, saying only that the two who threatened him were "young." McGarrett calls off the alert, saying "someone's trying to pull something big."
At the jewellery store, the loot is loaded into an ambulance which departs with all the gang members.
Chin Ho reports to McGarrett there was little activity reported during the tsunami warning, other than a jewelry store robbery which was under control. After McGarrett arrives at the jewelry store, Chin reports that there was no record the crooks were booked anywhere.
Ted and Shirley return home, as do the other students in the ambulance.
McGarrett says he wants to know "every vehicle that passed through [police checkpoints] in the last twenty minutes." The total amount of loot was around six million dollars.
The Brain Trust members congratulate each other.
The Five-O team analyzes facts regarding the robbery and other recent events, noting that an ambulance is a clever way to move people through a checkpoint, and that whoever pulled off this plan would have to have knowledge of geophysics. Danno suggests that this is the work of the Brain Trust.
At the Brain Trust house, McGarrett confronts Ted with his suspicions. He says that it is convenient there were no witnesses as to where the students were during the evacuation. McGarrett says "I want this place taken apart."
When McGarrett brings up the murder of Kenji, some of the other students are shocked. One of them, Adrienne (Kathy Yano) says she's "not going to take the fall for murder." Shirley whips out her gun and threatens everyone despite Ted's attempts to calm her down. Danno sneaks up behind her and disarms her as she shoots into an aquarium. Reaching into the aquarium, Danno finds the stolen jewels.
McGarrett tells Ted, "That's very clever, but that's been your problem from the very beginning -- you think you're smarter than anyone else." As the students are booked, McGarrett tells Danno "Brilliance, like jewels, can be flawed."