Two men leave the dock of the H.M.S. Windsor in a lorry. The sailor on duty checks them out, and as they drive through the countryside, one man worries that their cargo will blow up, but his mate assures him that it’s safe. They pull over and a third man, Felix de Burgh, meets them. He pays the thieves and drives off.
Harris and Peters are at a garage, waiting for Felix to arrive with the crate. He pulls up and they let him in, and Harris opens the crate to make sure it contains what they paid for. Felix opens a smaller box filled with fuses, while Harris and Peter confirm that the crate contains a World War II naval mine. Felix says that it’s the perfect weapon for the perfect murder.
Later, Harris arrives at the Glendure Hotel in the Scottish countryside and checks in under a false name. Felix comes down and glances briefly at his associate. McGill is in the lobby, watching both men. After they leave, he gets Harris’ room number from the ledger and goes upstairs to his room across from Harris’. Once Harris goes to Felix’s room, McGill uses a skeleton key to break into Harris’ room. As he searches the place, Harris comes in and demands to know why he’s there, and starts to call the police. McGill reveals that he knows who Harris really is, and Harris quickly hangs up
McGill says that he knows Felix is there, and Harris wonders what he wants. The ex-agent says that three of George Masters’ friends are registered at the hotel under assumed name, and George’s holiday home is ten miles away from the hotel. He advises Harris to give up whatever he has planned, warning that they’re amateurs, and leaves. Felix is hiding down the hallway and watches McGill go back to his room.
McGill takes a paper from his suitcase and leaves. Felix, Harris, and Peters are in the lobby and watch him drive away. Felix figures that he’ll be back, but tells his partners that they can’t continue letting George blackmail hem even if he’s hired McGill.
At the Masters estate, George’s wife Lucinda takes a call from Felix. He confirms that she hasn’t seen McGill, just as McGill pulls up to the manor. Lucinda realizes that he matches Felix’s description and hangs up just as George comes in the room. At the hotel, Felix tells Peters that they should be grateful that Lucinda hates George as much they do.
In the manor study, George strokes Lucinda’s hair and kisses her. His assistant, Crick, announces that McGill is there. As Crick goes to get him, George tells Lucinda that McGill is helping him compile information on a prospect. He escorts his wife out the other door and angrily tells her to keep her hair long. McGill arrives and tells George that Harris is holed up at the hotel with two of George’s other “friends.” George is shocked that they know each other, and McGill reports that they’ve been holding secret meetings all over London. McGill finishes that he’s done and demands his $500 plus expenses. George demands more reports, but McGill says that he’s resigning. As far as he’s concerned, his job to track suspected industrial spies is finished. He figures that they’re not after George’s business and doesn’t want to get involved. McGill admits that he told them to call off whatever they had planned, but George isn’t satisfied and tells McGill to go back and find out what they’re up to. Until then, he won’t pay. When McGill balks, George summons Crick in and points out that McGill is operating without a license and carrying a gun. McGill figures that George is blackmailing the three men, and slams the door into Crick. He takes out the man after a vicious fight, and George quickly gives McGill his money.
McGill drives back to the Glendure and tells the receptionis, Jean,t that he’s checking out. He enters his room and finds the three men waiting for him. Felix asks what his business is, and McGill tells him that it’s none of theirs. They want to pay him 5,000 pounds to forget them, but McGill refuses and figures that they plan to kill George. Felix insists that there’s no murder, and McGill suggests that they go back to the city and drop their plans. He suggests that they go to the police and warns that he has nothing to say to the police as long as George is alive.
Crick drives George to the hotel and tells Jean that his boss wants to see her outside. She goes out and George says that his friends are preparing a surprise party, and he wants to surprise them first. He pays her to confirm the three men are at the hotel and checked in that day, and tells her not to mention his questions to anyone. Once Jean goes inside, George wonders if Crick is becoming ambitious and his employee assures him that he’s not before driving off.
Peters sabotages McGill’s engine and gets clear as slips away. When McGill starts the engine, nothing happens. Lucinda gets in her nearby car and offers him a lift to the nearby garage. Peters and the others follow after them.
George goes into London to the hair salon that Lucinda is supposed to be visiting. He questions the hairdresser, Marie, and figures that Lucinda isn’t there despite her denials. He barges past her and searches the place, finds out his wife is gone, and leaves.
Lucinda offers to put McGill up for the night and flirts with him. When he makes it clear he’s not interested, she takes a side road and the three men cut them off. Felix fires a warning shot and introduces Lucinda as George’s wife, and then knocks McGill unconscious. Lucinda tells Felix when they’ll be at the party that night at their boathouse, and he tells her to make sure that George goes in first. He assures her that it’ll work and then they’ll soon be together. Harris and Peters have second thoughts about a second murder, but Felix points out that they can’t explain their presence at the hotel under false names. They dump the unconscious McGill in their car and walk to the lake. Felix points out the boathouse and reminds them that George doesn’t go there very often. He warns that George will keep blackmailing them or send Crick to kill them, and Peters gives in. Harris still has doubts, and Felix says that they’ll knock George out at the boathouse, put him in the boat with McGill, set the wheel, and let it go. It’ll hit the mine in the channel and it will look like an accident. Harris finally agrees and they go back to the car.
The three men drive McGill to the boathouse and order him out at gunpoint. Inside, Felix gets out a wetsuit while McGill tries to turn Harris against him. Felix shoves him around over Harris’ objections, and McGill warns Harris to find out how Lucinda fits into it. In the next room, Felix shows McGill the mine while Peter rigs it.
Lucinda returns home and George says that he’s not going to the party. He starts strangling her with her own hair but relents after a moment and says that he’s going to London. George takes her car keys and says that they’ll go together, and asks how Felix is. He tells his wife that Felix is at the Glendure with Harris and Peters, and they’re planning to kill him. George figures that Lucinda introduced the three men, and that Lucinda and Felix are having an affair because he wasn’t blackmailing Felix. When Lucinda refuses to give him her rings, George calls Crick in and has him take her rings. Furious, Lucinda throws them at George and says that she’s glad to get rid of him. He takes her necklace and earrings, and says that she can go back to her lover as penniless as when he found her. Crick throws her out and George tells him that they’ll take the boat across the loch to the airfield and fly to London.
At the boathouse, Peters boasts about their plan. McGill warns him that Felix won’t stop after he takes Lucinda. Intrigued, Peters asks what he means, just as Felix and Harris rejoin hem. Harris gets into the water and takes the mine out into the channel. Meanwhile, Felix secretly checks his gun and makes sure he has enough bullets.
Peters tells McGill that he made a mistake and George found out, and he’s tired of paying. McGill trips him and climbs out the window. Felix comes back in and finds the stunned Peters, and runs outside. McGill tries to run but trips, and Felix orders him up... just as Crick and George drive up. Felix shoots Crick and orders George to get the man inside.
Once they’re in the boathouse, Harris returns and is shocked to see another man dying because of their scheme. Felix demands to know where Lucinda is, Crick dies and refuses to get him into the boat. Felix gives him the gun and tells him to shoot if he has to, and then helps Peters load Crick in the boat. Once they’re alone, McGill keeps working at Harris, asking if three deaths are worth his peace of mind. George offers to pay Harris back and is surprised when Harris thinks that he was blackmailing Felix.
Felix comes in and Harris tells him what George said. The leader says that it’s too late for a deal, and McGill figures that Felix set the whole thing up to get Lucinda. He orders Harris to give him the gun and says that they’re all getting what they want. McGill points out that when Felix gets Lucinda, he’ll get George’s blackmail business as well. Peters takes the gun and figures that Felix set them all up. Harris refuses to kill anyone, and Felix lunges for Harris’ gun. Peters shoots him and McGill runs out and leaps into the loch. Harris tries to stop Peters, but Peters shoves past him, goes out on the dock, and fires at McGill.
McGill dives underwater and Peters keeps shooting, as Lucinda comes in and sees Felix dead on the floor. George runs out to the boat, starts it up, and takes off down the channel. McGill makes it to shore and shouts a warning, but George doesn’t hear him. Peters finds McGill and prepares to kill him, but Harris grapples with him. The gun goes off in the struggle, killing Peters, and Harris runs off.
George’s boat hits the mine and is blown up. McGill orders Harris to untie him, and then tells him to stay there and wait for the police. He looks at the grief-stricken Lucinda and then drives to town to get the authorities.
Written by Gadfly on Sep 25, 2015