Various shots show a City and County Ambulance driving at high speed with a police escort. It arrives at Castle Memorial Hospital. Danno is accompanying Marine Lance Corporal John T. Auston (Yaphet Kotto), who was hit by a baseball bat during a practice session of the baseball team that Five-O sponsors. The bat slipped out of a kid's hand and hit Auston in the forehead.
Dr. William Hanson (Jeff Corey), acting hospital chief of staff, examines Auston and orders him to be taken to the Emergency Treatment Ward. Auston is on leave from Vietnam, according to Danno, who checked his ID on the way to the hospital. As he is being prepped in a third floor room, Auston starts hallucinating. He grabs the gun from Peter Miller (Seth Riggs), a cop accompanying him, and shoots Danno in the abdomen. Miller, who is knocked down, gets up and is shot in the leg. Miller is dragged away from the scene by Dr. Cutter (Lawrence Templar). Auston then takes Miller's holster and gun, thinking he is back in Vietnam, and that Danno is his sergeant. He tells Danno, "We've got to hold this hill."
McGarrett arrives quickly at the hospital. From outside the room where Danno is wounded, McGarrett calls to him and Danno responds, but Auston cautions Danno against saying anything else: "It's a Viet Cong trick." Despite the advice of HPD Lt. George Kealoha (Doug Mossman), McGarrett tries to go down the hallway using a metal shield, but he is shot at. McGarrett talks to Cutter, who was in the room when Auston went beserk, trying to determine how badly Danno is wounded. Chin Ho tells McGarrett, "It won't help Danny any blowing your cool." Danno tries to convince Auston that they are not on a hill, but he buckles up with pain as Auston says he is going to "take a look around the terrain." Danno tells Auston that they are in a hospital and that he got hit with a bat at a baseball game, but Auston just says, "Anything you say. Now, you lay there and be quiet and I'll hold these VC's off and we'll get that first aid to you."
McGarrett is just about to go down the hallway again, when he is stopped by Hanson, who says that nobody goes down that corridor which is an intensive care unit. Hansen tells McGarrett, "There are patients in those rooms in critical condition. Gunfire can induce shock. Shock can kill anyone. Or possibly all of the patients in that intensive care section. People just out of major surgery, cardiac patients. Do you want to kill them? Their deaths would be on your hands." McGarrett relents, but then suggests using tear gas, which Hansen also nixes, saying "You fill that room with tear gas, you'll induce a coughing spasm in Danny. You start him coughing with a stomach wound and you'll decrease his chances of surviving by 90 percent. Go downstairs to the nursery and tell that to the newborn babies when the tear gas comes in through the ventilation system or the operating room."
Meanwhile, Auston tells Danno to lay still and be quiet "and we'll get you to that hospital that you've been dreaming about." Danno pulls his gun on Auston but passes out. Auston takes the gun, saying using that gun with the one he took from Miller, he "could defend the city of Saigon."
McGarrett thinks about other options to deal with the crisis, but Hansen has no easy solutions. McGarrett talks to Dr. Shirmer, head of the hospital's psychiatric service who says it's possible that the blow to Auston's head caused an acute psychotic breakdown which is causing him to relive a traumatic war experience. When McGarrett asks, "You mean, he thinks he's back in Vietnam," Shirmer says "He doesn't think he is, he is in Vietnam."
Outside the hospital, reporter Jack Francis from KGMB, Channel 9 in Honolulu, is doing live coverage of the incident. On the third floor, McGarrett considers rescuing Danno via the ventilation ducts, but they are too small. Trying to approach the room from outside is too dangerous. McGarrett tells his team to contact the Marines locally and Colonel Cardell in particular. He also asks for Charley Takahashi (Danny Kamekona), an HPD sniper, to come to the hospital.
Hansen reports there are problems with some of the patients in that wing of the hospital. A girl needs a technician to operate a kidney machine in 15 minutes, and in other rooms are cardiac patients. In room 306, a woman is visiting her father.
Danno is still trying to convince Auston that they are in a hospital. Auston replies, "You're hoping to crawl out of here and go back to the old man and tell him that I ran out on my assignment and had the VC's walk right in. Is that your bag, is it? You're still trying to hang something on me. Isn't that right? Isn't it, sarge? Well, I'm not gonna do it. I'm gonna stay right here and see that you live. And how are you gonna live with that? How are you gonna live with the fact that your life was saved by a Corporal John T. Auston? It's gonna drive you straight up the wall. And I hope it turns you around."
McGarrett tells Kealoha he wants a mobile crane from the electric or telephone company with a basket stretcher there right away to remove the girl with the kidney problem via the window in her room. Shortly after this, Mary Karabinos (Gina Villines), the woman who is visiting her father in room 306, comes out into the hallway and starts screaming because her dad is having a heart attack. Auston thinks she is a Viet Cong woman shooting at him and starts firing back. As Danno grabs at Auston, McGarrett rushes down the hall and pushes Mary back into the room where he immediately starts to perform chest compression on her father.
McGarrett tells Mary to phone the hospital's desk and get Hanson. Auston is not happy that Danno interfered while he was shooting, saying "No telling what they're liable to do now that they've got us spotted." Danno tells Auston to leave a gun and go get help, but Auston replies, "No dice. That way neither one of us will get through. We're gonna wait right here until the boys get here. Now, you gotta wanna live to live. So fight. Hang on."
The mobile crane has been quickly obtained and via the outside of the building it takes Hansen up to room 306 where he attends to Mary's father. Auston can hear the sound of the crane outside the corner of the building, which starts to make him nervous he thinks this is the sound of military vehicles. KGMB's Francis outside says, "There are reporters here on Oahu who in the past have taken stands against Steve McGarrett, head of Five-0, our state police unit. But those voices are silent this afternoon." The crane is used to remove the girl with the kidney condition.
Colonel Lew Cardell (L.Q. Jones), Marine Operations Officer at Camp Smith arrives. He talks to a Marine in the personnel office at the base who won't give any information about Auston to Chin Ho and tells him to co-operate fully with Five-O. Auston, thinking that Viet Cong are going to fire mortars, throws a chair through the window of the room and starts shooting at the crowd below. No one is hurt. Chin Ho and Cardell brief McGarrett on Auston, who is going to Washington to get a medal, so Chin says "it's got to be a big one." A search is on for Lance Corporal Burt Rosen, a man from Auston's outfit who arrived together with him from Saigon.
McGarrett tells Chin and Kono to get to the rooms on the third floor near Auston's via the crane. He then goes to the roof of the hospital where HPD sniper Charlie Takahashi is preparing to take aim at Auston in the room below. McGarrett doesn't want Auston killed, but Charley says only winging him would be very difficult. When Takahashi says he will "try" to wing Auston, McGarrett says "Try is not good enough. I can't risk it. Wrap it up." McGarrett tells Cardell, "When those doctors tell me that those patients are out of danger, we're going in. And if there's only one way left, we take it. Straight in."
McGarrett wants to go down the hall with six armed HPD men using shields, but Cardell does not agree with this approach. Shirmer says, "Auston is in Vietnam reliving some battle or fight, or skirmish he went through. The police, McGarrett, everyone else is the Viet Cong." But McGarrett questions why is everyone the Viet Cong, "Why doesn't he think we're his relief company?" McGarrett and the 6 HPD men are just about ready to go down the hall, when Cardell says that Auston's buddy Rosen (Douglas E. Barden) has been located. McGarrett talks to the man on the phone and finds out that "[Auston's] squad was rearguard on a sweep. The VC caught us on the flank. Big John's squad was all wiped out. They were holding a hill, a pivot for the company. John was the only one who made it. He was stuck up on that hill for 11 hours with his platoon sergeant. [Auston] was hit in the chest... the shoulder. Shrapnel from mortar fire." Rosen says that Auston and his sergeant may have been rescued by a helicopter, which gives McGarrett an idea. He orders a chopper from HPD and requests a corpsman's uniform.
Thinking that the Cong are "moving the mortars up again," Auston says he is going to open up with his gun and make them back off, but Danno convinces him not to do this, because that likely will result in death for both of them. Auston agrees, saying, "I have to stay here with you and we'll fight them together."
Outside, dressed in the uniform of a medic, McGarrett boards the helicopter after some instructions from Cardell and Shirmer. Chin Ho and Kono down the hospital corridor start yelling "Corpsman," and Auston says to Danno "They're here." Using a ladder below the helicopter, McGarrett climbs down into the hospital room through its window. Auston orders McGarrett around until McGarrett tells Auston that he is wounded with shrapnel in his shoulder. When Auston insists that the "sarge" be treated first, McGarrett says "He's already dead." Auston screams, "No! I gave him my word that I'd get him out alive. And then he went and died on me. You didn't even fight. You ran! Because you didn't wanna owe this black man nothing. He didn't even give me the chance to hear him say John or call me 'nigger'." McGarrett gives Auston a shot. As he loses consciousness, Auston says, ""He ran out on the living. Like a thief. You know, old buddy, up there on that hill I couldn't even think of praying or anything else. Hang on to that lousy hill. And we did it. Me and my sergeant. We held it, and we held it, and we held it, and we held it and we held it "
Doctors rush into the room and check out Danno; they tell McGarrett that he is going to make it. The episode ends with a shot of Auston and McGarrett on the floor as the camera backs away down the hall with military-sounding music on the soundtrack.