It is the morning of 23rd December at the City & Colonial Bank in Haversham, England, and the staff are arriving for work. They make small talk and contribute to a collection for their Christmas party that evening. When manager Harry Fordyce [Peter Cushing] arrives, he cleans the bank plaque outside and then, after entering the bank, points out that Christmas cards should not be out on display. He inspects the bank to ensure everything is clean and in place and reprimands chief clerk Pearson [Richard Vernon] because the nib of a pen is not in optimum condition. Fordyce calls Peter [Barry Lowe] into his office to question him about an irregularity in the balance of his till. Peter protests his innocence but Fordyce is suspicious that Peter may have deliberately falsified the books with Pearson. Peter claims it was all an innocent mistake and the money was later returned. Fordyce questions Pearson about it too. Pearson is more relaxed compared to Fordyce's strict personality and following the accusation Pearson requests a transfer to another branch. Fordyce refuses, claiming it would be dishonest given this irregularity in the books and suggests he may even have to sack Pearson, which would ruin Pearson's career. When the bank opens for business, the first person to arrive is Colonel Gore Hepburn [Andre Morell] who asks to see the manager. Fordyce reluctantly agrees so Pearson shows him into Fordyce's office. Hepburn tells Fordyce and Pearson he is from head office, specifically the bank's insurers, and it is his job to visit the banks to ensure that all proper security is in place. Hepburn reprimands them for letting him in to the manager's office without checking who he is first, saying he could be a gunman. Fordyce and Pearson agree to be more vigilant next time and Pearson leaves the office. Fordyce tells Hepburn he is thinking of letting Pearson go, and Hepburn expresses surprise and says he knows how long Pearson has worked at the branch. Fordyce's telephone rings. It is his wife; she sounds desperate and tells Fordyce to "do whatever he tells you" before Hepburn cuts the call off. Hepburn tells Fordyce there are two men at his house with his wife and child and they will electrocute his wife if Fordyce does not comply with his demands. Hepburn tells Fordyce to call Pearson in, and instruct him to move Hepburn's car into the car park and bring his luggage in. After the luggage has been brought in, Miss Pringle [Edith Sharpe] brings in some tea. Hepburn asks her if they are having a Christmas party and gives her a £5 donation towards it. After she has left, Hepburn asks Fordyce if he ever contributes to the Christmas party but Fordyce says he does not ingratiate himself with his subordinates. Hepburn tells him he does now and demands his £5 back. Hepburn and Fordyce leave the office to inspect the bank's alarm system. They check the alarms at the tills of Peter and Sanderson [Norman Bird]. After they have moved on, Sanderson asks Pearson if he has checked with head office if Hepburn is really who he says he is. Pearson hasn't, so Sanderson makes the telephone call to head office. However, the lines are busy and he can't get through so he asks to be called back. Back in the manager's office, Fordyce tries to convince Hepburn that the bank does not hold a lot of cash in stock. Hepburn slaps Fordyce and tells him this operation has been a year in the planning and he knows they have about £97000 in stock to pay various company wages before Christmas. Hepburn explains his plan for going to the strong room, but before they go Hepburn asks for a drink. While they have a whiskey each, Hepburn points out the uncharitable characteristics of Fordyce's personality. Fordyce tries to defend himself and becomes angry but Hepburn quickly defuses the situation and ensures Fordyce can repeat the plan for going to the strong room. They call Pearson in to go to the strong room together because Pearson and Fordyce each have one of the two required keys. Pearson switches off the magic eye alarm system and they go downstairs. Fordyce and Pearson unlock the strong room door and Hepburn pretends to start his inspection. They dismiss Pearson and once he has returned upstairs, they retrieve Hepburn's luggage from Fordyce's office. The bags are full of books which Hepburn empties out while Fordyce tries to open the safe. Initially, in his panic, Fordyce is unable to remember the combination but manages to compose himself and after a few attempts he opens it. They take out the wads of money and pack them into Hepburn's bags. Unknown to Fordyce, Hepburn slips one of the wads of money into Fordyce's suit jacket pocket as they pack the last bag. As they exit the strong room, they forget to close the inner door before they close the outer door. A light flashes to indicate they only have 30 seconds to reopen the outer door and close the inner door before the alarm goes off. Fordyce starts to panic but just manages to unlock the outer door in time to close the inner door before the alarm sounds. They quickly return to Fordyce's office with bags. Hepburn explains to Fordyce it is now time for him to leave. He says one of his accomplices will be watching the bank, and if there is any sign of the police or any alarms for one hour, they will kill Fordyce's wife. Meanwhile, back behind the tills, the telephone call from head office has finally come through but gets cut off before Peter or Pearson can verify Hepburn's identity. Peter brings Hepburn's car back to the front of the bank while Fordyce helps Hepburn out with his bags. Hepburn drives off and as Fordyce returns to his office the telephone call from head office comes through again, which Pearson answers. Pearson enters Fordyce's office and confronts Fordyce, asking what is going on. Head office has confirmed Hepburn was not genuine and Pearson is suspicious of Fordyce's nervous behaviour. Fordyce tries to protest his innocence but Pearson knows now the bank has been robbed. Fordyce finally admits what has happened but explains he is unable to do anything because his wife and child are being held hostage. However, Pearson has already rung for the police. Fordyce begs him to stop them but Pearson says all the other staff also know what is happening because they heard Pearson call the police. Fordyce says the staff must help him because his family are all he has got. The police arrive: Det. Sgt Collins [Charles Morgan] and Det. Constable Kane [Alan Haywood]. Fordyce claims there has been a mistake and Pearson goes along with him, saying they made a mistake with Hepburn's identity and there is not a large sum of money missing after all. Peter also joins in, saying it was partly his fault for not telling Pearson and that Pearson panicked. They say if Hepburn is stopped, the entire bank staff will be in trouble for their mistake. While the constable goes back out to radio through the mistake, Fordyce invites the Sergeant into his office for a drink since it is Christmas time. Fordyce nods his thanks to his staff who have supported him. As Fordyce and the Sergeant have a drink, Fordyce is on edge but the Sergeant explains they arrived without any sirens. He also mentions they have a new Inspector who was very keen to get going when the call came in from Pearson. As the Sergeant goes to leave Fordyce's office, Det. Inspector Mason [Kevin Stoney] arrives with Hepburn in handcuffs, much to Fordyce's shock. Fordyce still tries to maintain that Hepburn is with the bank's insurers at head office and there has been a mistake and he can vouch for Hepburn. However, the police bring in Hepburn's bags and open them to reveal the money. Hepburn says he and Fordyce planned it together. Mason has arrested Hepburn before so the Inspector accuses Fordyce of being involved as an accomplice. Fordyce breaks down and explains he was forced into it and his wife is being held hostage. Mason calls Fordyce's home number; his wife and son are there and everything at home is fine and they have not been held hostage. Fordyce still tries to protest his innocence but while trying to explain, the wad of money falls out of his pocket. Mason wants to take Fordyce and Hepburn to the police station but before they leave, Hepburn explains the voices of Fordyce's wife and child on the phone were false ones on a tape recorder. Hepburn says his accomplice is not Fordyce because he would use a better man than that. Fordyce still has to go to the police station to make a statement but before they leave, Fordyce calls Pearson over. Fordyce now realises how he has treated the others badly and admits failing completely in his duties. He thanks Pearson and says he will see him later at the Christmas party. At the door of the bank, Fordyce turns and again acknowledges the support his staff have shown him.