In New York City, real estate investor Kevin Lenahan has a hair-brained scheme to buy a thirty-two screen movie theater complex in which each theater only has eighteen seats. When banks deny his loan request, he approaches a loan shark named Palazzi, who is actually a gangster. Police raid Palazzi’s office while Kevin is making his loan request and arrest him in the process. Kevin’s lawyer works out a plea deal by which Kevin will only do one year in prison, but Palazzi, who has vowed revenge, will be in the same prison, serving a ten-year sentence. In the courtroom, Kevin pretends to be insane to avoid going to prison. The court sends him to Empire General Hospital for evaluation. When psychiatrists determine he is faking his mental condition, hospital administrator Arthur Chambers plans to send Kevin back to jail in the morning. Meanwhile, Hurricane Sam approaches New York City. Since Empire General is located on a small island in New York harbor, Maggie, the head nurse, requests some of her nurses remain overnight in case there are problems, but Chambers refuses the overtime request. He tells his administrative assistant, Rachel Atwood, that a fill-in emergency room doctor, Edward Slattery, will arrive shortly to help out. When Kevin starts a ruckus in the psychiatric wing, Chambers tells guards to lock him in a private room for the night. When the other psych patients protest Kevin’s punishment, Chambers threatens to have them all transferred to a hospital for the criminally insane. Just then, the hurricane knocks out the electricity. The patients take this opportunity to escape, locking Chambers and the guards in the psych ward. Kevin goes to Chambers’ office to look at his file as Rachel Atwood finds him there when she goes to the office to consult the disaster preparedness manual. She assumes Kevin is the missing Dr. Edward “Eddie” Slattery and tells him to go to the emergency room (ER) right away. Kevin puts on a white coat and finds chaos in the ER. Dr. Foster, a longtime physician at Empire General, refuses to treat any patients and recommends they not admit anyone since dealing with patients during a blackout is a “malpractice time bomb.” Kevin spies the exit door, rushes out, gets in an ambulance and drives away. However, the rainstorm is so intense, he cannot see well and drives off the causeway connecting the island hospital to the mainland. He escapes before the ambulance sinks into the water. The hospital’s back-up generator comes on briefly, but soon goes out again. First-year intern, Dr. Joffe, suggests they connect the generator to the ambulance batteries. When Kevin returns to the ER, nurse Maggie gives him files on a half dozen patients needing treatment. Kevin acts authoritative and gives the responsibility to other ER staff, saying he will trust their recommendations. When people obey his orders, Kevin realizes it is easier to pass himself off as a doctor than a lunatic. However, Louis, an orderly, recognizes him from the psych ward, but decides not to say anything and enjoy the fun. Kevin goes to the waiting room, advising patients that exercise is good for them and recommending they treat each other. Young Dr. Joffe comes to him with questions, but Kevin suggests he trust his own gut instincts. Worried about malpractice lawsuits, Dr. Foster has concerns about Kevin’s methods, calling him a “gypsy doctor.” Meanwhile, in the psych ward, the patients have Arthur Chambers tied up. They start a list of changes they want implemented before they agree to release him. Chambers refuses to sign their list of demands and tells them Kevin was an undercover agent from the board of health, but they do not believe him. A pipe bursts, flooding the basement and orderlies say it will be morning before they can possibly get the generators working again. Kevin suggests they move a generator from the helicopter landing pad to power the ER. Rachel Atwood goes to the drug detoxification unit to get help moving the generator, but none of the patients are willing to help. Kevin goes to the detox unit promising to give the patients their methadone pills if they will help move it, and they all pitch in. Soon the ER has power again, but the rest of the building does not. Since the upper floors have no air circulation, Kevin suggests moving the helicopter into the building and placing it beside the elevator shaft to get air moving to the upper floors. Kevin and Rachel go to the kitchen to fix sandwiches for the patients and develop a bond while discussing how to help the patients. Kevin visits Tommy Pinto, a patient who fell off the hospital roof and has no feeling in his legs. Tommy requires immediate surgery or he will be crippled for life. A make-shift operating room is set up in the ER and Kevin persuades Dr. Foster to do the surgery. In the psych ward, Chambers finally signs the list of demands and the patients contact Rachel via walkie-talkie to get her to implement the demands before they will release Chambers. When Rachel is resistant, Box, the leader of the psychiatric patients, demands to deal with Kevin Lenahan. Rachel does not know anyone named Kevin, but when they describe him, she realizes they are talking about the man she knows as Edward Slattery. Rachel confronts Kevin, fearful she will get in trouble for all the things she authorized at his recommendation. Kevin assures her they dealt successfully with a crisis and refuses to help get Chambers released if they intend to send him back to jail once the crisis is over. He makes his own list, demanding to be set free and also demanding none of the other psych patients be sent to the institute for criminally insane. Rachel agrees. Kevin gives the word to free Chambers, and Rachel gives him the keys to a speed boat docked at the pier. Chambers is upset to see what has happened to the hospital and lashes out at Foster and Rachel. However, Dr. Joffe insists they did what had to be done under the circumstances. Nonetheless, Chambers fires Rachel. Kevin speeds off in the boat, but as he glances back at the hospital, he sees plumes of smoke from a fire set by a patient. Kevin rushes back and orders the hospital evacuated. He uses a hose to put out the fire, but when Chambers makes threats against him, Kevin turns the hose on him. The patients and staff defend Kevin, saying he saved the hospital. Kevin lambasts Chambers for criticizing his staff rather than empowering them. If Chambers had done proper maintenance, many of the problems would not have occurred. He suggests the press will be interested in covering this story. Meanwhile, Stucky, the patient who set the fire, takes Rachel hostage. Seeing that Stucky has a walkie-talkie, Kevin pretends to be several people talking on the device to confuse Stucky. Kevin and Stucky fight and Kevin knocks him out. Grateful, Chambers tells Kevin to leave, suggesting that his file was likely destroyed in the fire. As Kevin gets into the speedboat, Rachel follows him, asking why he could not have been the real Dr. Slattery. Kevin invites her to dinner and she accepts. The two speed off toward New York City.