Cry Terror!

In New York City, Roger Adams, the chief executive of Twentieth-Century Airline, receives a letter threatening to blow up one of the company's airplanes in mid-flight unless half a million dollars is paid. As proof of the letter's legitimacy, Adams receives a phone call instructing him where to have the airplane's crew search for the bomb, which is then safely disarmed. Electronics expert Jim Molner hears the news of the bomb threat in his small shop and becomes agitated when the report describes the major ingredient of the bomb as a powerful, doughy substance used in the last war. When Jim learns that the bomber has contacted the airline again to announce another bomb has been planted in a cargo hold, he hastens home. There Jim's wife Joan listens with shock while he reveals that he constructed the bomb planted on the plane. After hearing news reports announcing that the threatened flight has landed safely, Jim explains that he was recently contacted by Paul Hoplin, a demolitions expert in Jim's military unit during the war. Claiming to have inside government contacts, Hoplin convinced Jim to devise a compact bomb as a model that he would then offer the army. Unable to contact Hoplin since then, Jim is now certain that Hoplin used his bomb design as a model to create others. The Molners are then interrupted by the arrival of Hoplin who forces his way into the house at gunpoint. Hoplin admits to using Jim, but suggests that the authorities will believe Jim is involved in the plot. Hoplin then declares he is kidnapping the Molners and their young daughter Pat and forces the family into a car driven by his accomplice, ex-convict Steve. Meanwhile, Adams and his security head, Mr. Pringle, contact the Federal Bureau of Investigation and special agent Frank Cole is assigned to the investigation. Shortly thereafter, Adams is contacted by the bomber again and instructed to place an advertisement in the afternoon newspaper's classified section indicating that the ransom will be paid. The caller reveals another bomb has been planted on an unspecified flight and will be detonated if the ad is not run. Cole discovers that the luggage containing the bomb belongs to a female passenger who deplaned in Chicago and, examining her plane seat, the agents find a piece of chewed gum on which they begin running dental tests. Later that afternoon, Hoplin takes the Molners to an isolated estate, which has been secured by his other cohorts, Vince and Eileen Kelly. Upon finding the critical classified ad in the newspaper that afternoon, Hoplin orders Joan to pick up the ransom money and threatens to harm Pat if she declines. When Jim and Joan refuse to be separated from Pat, Hoplin orders Vince and Kelly to move Jim and Pat to another location, then leaves Joan alone with Steve. While Hoplin contacts Adams to direct how the money is to be paid, Joan is tormented by the advances of the unbalanced, drug-addled Steve. Kelly and Vince take Jim and Pat to Kelly's luxurious penthouse apartment, then contact Steve to reassure Joan of Jim and Pat's safety. Cole informs Adams that the bomb materials have been traced to Jim's shop, but despite the Molners' unexplained disappearance, they remain unsure of Jim's involvement in the plot. The next morning, Hoplin drops Joan at the bank with explicit directions on how to proceed. In the bank, Joan is taken to Adams and reveals that Jim and Pat are being held hostage to force her participation in the ransom pickup. Unaware of Hoplin's full name, Joan can only give a sketchy description of him and pleads with Adams and Cole not to disrupt the carefully timed pickup. Joan also relays that, in order to prevent police interference, Hoplin has planted another bomb in an unspecified populated area that will detonate by 1:45 that afternoon if he has not received the money by 1:30. Before departing with the money, Joan describes Steve and when shown a sketch of Kelly compiled from passenger descriptions, Joan identifies her. Joan then departs the bank with the money in a box and follows Hoplin's complex orders, which lead her to an empty car in an alley. While listening to police dispatches on the car's radio, Joan hears a message planted by Hoplin directing her to the address of Steve's apartment. Soon after, however, Joan panics when, inadvertently forced onto the wrong freeway ramp by a large truck, she is compelled to drive several miles out of her way. When Joan fails to arrive at Steve's on schedule, Hoplin telephones Vince and is about to tell him to kill Pat and Jim, when Joan arrives. Convinced that Hoplin intends to murder his family despite the ransom payment, Jim plots to escape and summon help. Discovering an unlocked door off the roof-top balcony, Jim finds that it leads to the elevator shaft and decides to make his escape through it that night. Meanwhile, Hoplin leaves Joan alone with Steve, who again makes crude advances. When Steve attacks Joan, she slashes his throat with a shard of broken glass. Later, when Hoplin returns, Joan hides Steve's body and tells Hoplin that Steve departed in search of drugs, but Hoplin suspects the truth. That evening, Jim escapes down the elevator shaft and is nearly caught by Kelly, who has gone out for groceries. Meanwhile, Cole receives Kelly's name and address through her dental records. Upon reaching a lower floor in the building, Jim uses a tenant's phone to contact the police. Just as Vince discovers Jim's escape, Cole and the police arrive at Kelly's penthouse and arrest the pair, who refuse to divulge Hoplin's location or escape plans. When Joan demands to be reassured that Jim and Pat are still safe, Hoplin telephones Kelly's apartment where Cole and the others are waiting. Just as Joan speaks with Pat, however, Hoplin sees headlines of Vince and Kelly's arrest in the newspaper. Hysterical, Joan escapes and Hoplin pursues her. Darting into a subway entrance, Joan pleads with a man to summon the police. Having finally learned of Hoplin's location from Vince, Cole, Jim and the police hurry there and, alerted by the man Joan saw, enter the subway tunnel. Exhausted, Joan collapses on the tracks and Hoplin is accidentally electrocuted when he stumbles against the power rail. Jim and Cole then rescue Joan before an oncoming train reaches the station.