Fact1: Royal Navy sloop HMS Amethyst sails up Yangtze River on way to Nanking to deliver supplies to British Embassy, Fact2: Captain After taking stock of is replaced by Lieutenant Commander John Kerans position, Fact3: Kerans decides to risk steaming down Yangtze at night without pilot or suitable charts, Fact4: merchantman receives brunt of PLA artillery while Amethyst presses, Fact5: Tamiroff flees heading for mouth of river
Output: On 19 April 1949, the Royal Navy sloop HMS Amethyst sails up the Yangtze River on her way to Nanking, the Chinese capital, to deliver supplies to the British Embassy. Suddenly, without warning, Peoples Liberation Army PLA shore batteries open fire and after a heavy engagement, Amethyst lies grounded in the mud and badly damaged. Fiftyfour of her crew are dead, dying or seriously wounded while others deteriorate from the tropical heat and the lack of essential medicines, including the ships captain, who dies of his wounds. An attempt to evacuate the wounded is only partially successful  the officers of the Amethyst become aware that two Petty Officers were captured by the PLA and are being held at a nearby military hospital. After taking stock of their position, the Captain is replaced by Lieutenant Commander John Kerans Richard Todd, who had been serving as a Naval attache in nearby Nanking but rushes to the beleaguered ship to take command. After an attempt by HMS Consort to tow Amethyst off the mud bank fails, Lieutenant Commander Kerans decides to risk steaming down the Yangtze at night without a pilot or suitable charts. Before they can leave, however, the local Communist official Colonel Peng Akim Tamiroff makes contact with the Amethyst and at a meeting between senior officers makes his position clear: either the British government releases an apology accepting all responsibility for the entire incident, or the Amethyst will remain his prisoner. Similarly, he will not allow the two wounded sailors to leave unless they give him statements declaring the British to have been the transgressors, which they refuse to do. Kerans dismisses his demands but is able to manipulate Peng into the release of the Petty Officers; meanwhile, as talks progress he has the ship patched up and its engines restored. After some subtle alterations to the ships outline to try to disguise her, Amethyst slips her cable and heads downriver in the dark following a local merchant ship, which Amethyst uses to show the way through the shoals and distract the PLA. When the shore batteries finally notice the frigate escaping downriver, the merchantman receives the brunt of the PLA artillery and catches fire, while Amethyst presses on at top speed. Encountering an obstruction in the river in the form of several sunken ships, and having no proper equipment for charting a safe course, Kerans uses both intuition and luck to slip through before then reaching the guns and searchlights of Woosung. After she is inevitably spotted, the Amethyst is forced into a lengthy fight with the PLA batteries as she simply flees with all guns blazing, heading for the mouth of the river just beyond. As day dawns she finally reaches the open ocean, where she greets HMS Concord with the message Never repeat never has another ship been so welcome. She also sends a signal to headquarters: Have rejoined the fleet south of Woosung... No major damage... No casualties....God save the King! The film then ends with scrolling text reciting verbatim the message sent the very same day from King George VI, commending the crew for their courage, skill and determination.